204

CHAPTER 7

TRANSPORT PROPERTIES OF ZnX CRYSTALS AND THINFILMS

7.1 INTRODUCTION

Properties of semiconductors depend on the way they respond to the external force or

forces in a given environment. For example, the mechanical, electrical and magnetic

properties are the response to the mechanical, electrical and magnetic forces exerted on them.

In the recent years there has been tremendous interest in electrical characterization of

semiconductors and to relate the various results of measurements to the reliability and

performance of the devices made from the semiconductor compounds [1]. Analysis of the

various electrical measurements is of great importance in application point of view of the

semiconductors.

Despite the considerable interest in photo luminescent and electroluminescent,

structural and optical properties of II-VI compounds, few reports have been found for the

electrical transport properties of these compounds. This may probably be due to the fact that

many of these compounds possess very high resistivity at room temperature.

Electrical properties of II-VI semiconductor crystals as well as thin films are greatly

influenced by many parameters [2-25]. Temperature dependence of high field transport of II-

VI wide band gap semiconductors is of particular relevance to the large efforts at present in

order to produce A.C. and D. C. electroluminescent devices [42]. Electrical resistivity is one

of the most important electrical parameter of semiconductors [26-29].

7.2 HALL EFFECT MEASUREMENTS AT VARIOUSTEMPERATURES

7.2.1 HALL EFFECT MEASUREMENT SYSTEM

The Lakeshore 7504 series Hall Effect / Electronic Transport Measurement System

has been used to measure the electronic transport properties of electrically conductive

205

materials [30]. The system consists of advanced integrated hardware and software. The

system software controls system instrumentation during an experiment and determine sample

resistance, resistivity, Hall coefficient, Hall mobility and carrier concentration. The software

can control magnetic field during measurements.

The system consists of an electromagnet which can produce magnetic field of

maximum 10 kG at 10 cm air gap between two pole pieces of four inch diameter. The

magnetic power supply (LS 689) provides necessary current to the magnet. The current and

voltage limits of the power supply are 0 to 72 A and 0 to 32 V respectively. The gauss

meter (Model – 450) is used for magnetic field measurement.

7.2.2 VAN DER PAUW MEASUREMENT

Electrical properties of the materials play an important role in determining the

behavior of solid state devices and thereby their potential for such applications. Hall Effect

measurement is an effective tool to provide the information about basic material parameters

needed to find the suitability of its applications. In the present investigation, the Hall Effect

measurement was performed using system (Lakeshore-7504) under magnetic field of 3kG,

from room temperature to 120C.

The theoretical foundation of the Hall measurement evaluation for irregularly shaped

samples is based on the conformal mapping developed by van der Pauw [31-32]. The

resistivity, carrier concentration and mobility of the flat samples of arbitrary shape can be

determined without knowing the current pattern, if the following conditions are satisfied

1. The contacts should be sufficiently small

2. The contacts should be at the circumference of the sample

3. The sample should be uniformly thick

4. The sample should not contain isolated holes

Van der Pauw suggested different geometries of the samples such as circular, square,

rectangular and cross. The cross structure is generally used for films and other for bulk

crystals.

According to the investigations made by Danial W. Koon [33-36] the preferred

geometry is square rather than circle to reduce the effect of contact lead placement errors in

206

1

2 3

4

(a) (b)

(c) (d)

1

2 3

41

2 3

41

2 3

4

(a) (b)

(c) (d)

measurement of transport parameters such as resistivity and Hall coefficient. The square

shape is the most convenient sample shape to fabricate, and will reduce the effect of errors in

the van der Pauw method arising from either size or the displacement of contact leads from

edge of the sample. The lead placement in the square sample must be near to the corners as

shown in figure 7.1 (a),to minimize errors.

Figure 7.1 (a) Sample geometry for van der Pauw resistivity and Hall Effectmeasurement. (b) & (c) Schematic of van der Pauw configuration usedfor the determination of the two characteristics resistances RA and RB. (d)Schmetic of a van der Pauw configuration used in the determination ofHall voltage VH.

207

It is easy to show that for four contacts on the boundary of a semi-infinite plane sheet

the resistances R12, 34, R23, 41 satisfy the following relationship.

exp

tR 34,12 + exp

tR 41,23 = 1 (7.1)

By knowing thickness of the sample t, R12,34 and R23,41 , the above equation can be solved for

the resistivity of the material [37,38 ] and can be written as

2)2ln(

41,2334,12 FRRt (7.2)

where R12,34 =12

34

IV

(7.3)

The current I enters the sample through contact 1 and leaves through contact 2 and

V34=V4-V3 is the voltage between contacts 4 and 3. R23, 41 is similarly defined. The quantity

“F” is a transcendental function of the resistance ratio given as,

Rr =41,23

34,12

1412

2343

RR

VIIV (7.4)

OR

Rr =43,12

14,23

2343

1412

RR

IVVI (7.5)

Whichever is greater and F is calculated by solving the equation

2

)2ln(expcosh

)2ln(11 FarF

RR

r

r (7.6)

F = 1 when Rr = 1, which occurs with symmetrical samples like circles or squares, when the

contacts are equally spaced and symmetrical.

For each measurement points in a Hall experiment, up to 32 individual resistance

measurements are required to be made for both A and B type of geometries. Here, geometry

A corresponds to R12,34 and R23,14 and geometry B corresponds to R41,32 and R34,21. Each van

208

der pauw resistivity requires 8 measurements (terminal interchange and current reversal for

both figures 7.1 (b) and (c) and the Hall resistance requires 4 measurements (terminal

interchange and current reversal for above figure 7.1 (d). The sequence of measurement is as

follows.

Hall resistance measurements for +ve magnetic field, +B (4 measurements)

1. Zero field measurements (8 measurements)

2. Resistivity measurement for +ve magnetic field, +B (8 measurements)

3. Hall resistance measurements for –Ve magnetic field, -B (4 measurements )

4. Resistivity measurement for –ve magnetic field, -B(8 measurements)

In present investigations the experiment has been conducted with a magnetic field of

3 kG. By knowing the thickness “t” of the sample and measurement of voltage and current

with polarity reversal across the contacts, the resistivities for geometries A and B can be

calculated from the following equations [37, 38]

cmmIIIIVVVVcmmtf A

A .,.)2ln(,

23231212

14,2314,2343,1243,12

(7.7)

cmmIIIIVVVVcmmtf B

B .,.)2ln(,

41413434

23,4123,4121,3421,34

(7.8)

Here, 43,12V is the voltage measured between contacts 4 and 3, when positive forced current is

allowed to pass between contact 1 and 2. Similarly, 12I denotes +ve forward current

measured between contacts 1 and 2. The geometrical factors BA ff , are functions of BA QQ ,

respectively. They are given by

14,2314,23

14,2314,23

43,1243,12

43,1243,12

14,2314,23

43,1243,12

VVII

IIVV

RRRR

QA (7.9)

209

23,4123,41

4141

3434

21,3421,34

23,4123,41

21,3421,34

VVII

IIVV

RRRR

QB (7.10)

The relationship between f and Q is expressed by the transcendental equation

ff

QQ 2lnexp

21cosh

2ln11 1 (7.11)

The two resistivities must agree to within 10% of accuracy. If they do not, then the sample

is too inhomogeneous, or anisotropic, or has some other problem. If they agree, the average

resistivity is given by

cmmBAav .,.

2

(7.12)

Similarly with the help of some measurements of voltage and current along with the

magnetic field reversal, the two Hall coefficients are calculated by the following equations

13

31313131

42,3142,3142,3142,31 .

Cm

BIBIBIBIBVBVBVBV

TBmtRHC (7.13)

13

42424242

13,4213,4213,4213,42 .

Cm

BIBIBIBIBVBVBVBV

TBmtRHD (7.14)

where, RHC and RHD are the Hall coefficients for configurations shown in figure 7.1 and its

terminals interchange respectively. These two values should also agree within 10%. If they

do not agree, it indicates that the sample is too inhomogeneous, or anisotropic, or has some

other problem. If they agree, then the average Hall coefficient can be calculated by the

equation

13 .2

CmRRR HDHC

Hav (7.15)

From the average value of resistivity and Hall coefficient, the Hall mobility can be calculated

using the equation

210

T h e r m o c o u p l e

H e a t e r S a m p l e

T h e r m o c o u p l e

H e a t e r S a m p l e

112 .. SVmR

Av

HAvH (7.16)

where Av is the zero field resistivity.

The effective charge carrier concentration can be computed using the formula

eRn

He .

1 (7.17)

7.2.3 EXPERIMENTEL PROCEDURE

The variable temperature Hall effect measurements have been performed on ZnX

(X=Se,Te) crystals grown by DVT technique and ZnX (X=Se,Te) thin films deposited by

thermal evaporation technique as discussed in earlier chapter. A specially designed sample

holder (Scientific Equipments-Roorki) with built in heater and thermocouple was used in this

experiment. The sample holder is shown in figure 7.2.

Figure 7.2 A sample holder with heater and thermocouple.

211

T e m p e ra tu re in d ic a to rc u m c o n tro lle r

S a m p le H o ld e r

T e m p e ra tu re in d ic a to rc u m c o n tro lle r

S a m p le H o ld e r

The ohmic contacts were taken on the samples (crystals and thin films) with

conductive silver paste and copper wires. The samples were properly placed on the sample

holder and contact wires were carefully attached with the connecting tracks of the holder. In

case of the crystals, both ZnSe and ZnTe crystals were properly cleaned to ensure smooth

and flat surface area covered with the contact wires. Thin films were deposited on the small

glass substrates (area = 1 cm2) so that they can be easily placed on the sample holder.

A temperature controller cum indicator system of ON/OFF type was attached with the

sample holder heater circuit to perform the experiment at known and controlled temperatures

(from 30C to 120C) with an accuracy of ± 10C. The complete Hall Measurement system

along with the high temperature sample holder and temperature controller cum indicator is

shown in figure 7.3.

Figure 7.3 A complete Hall Measurement System (Lake Shore 7504) withhigh temperature sample holder and temperature controller.

212

Ohmic contacts are required for accurate and error free measurements of Hall Effect

to deduce transport properties of semiconducting samples under study. It is recommended

that we should test the current –voltage characteristics between the contacts to verify the

ohmic behavior of contacts of sample before beginning the Hall measurement experiment.

All the samples have been verified for four sets of contacts of the samples for their ohmic

nature and then further experiments were performed.

In the first step, I-V measurements were done for the sample using various contacts (R12,12,

R23,23, R34,34 and R41,41) without applying magnetic field. In the second step, Hall parameters

measurements were performed using the van der Pauw method at various magnetic fields

(+3kG to -3kG at the interval of 1kG) and at various temperatures (from 30C to 120C) for

grown crystals and thin films of ZnSe and ZnTe. Here the applied current range suitable for

particular sample is manually selected.

7.3 RESULTS AND DISCUSSION

7.3.1 RESULTS OF ZnSe AND ZnTe CRYSTALS GROWN BY DVT TECHNIQUE

7.3.1.1 OHMIC CONTACTS TO ZnSe AND ZnTe CRYSTALS GROWN BY DVTTECHNIQUE

Preparation of Ohmic contact requires special skills and knowledge of band structure

of semiconductor and contacting metal. It is all about the finding the suitable metal or alloy

or a particular phase of the metal/alloy so that it offers minimum barrier for charge carriers

moving across the interface. This can be achieved by using different metals/alloy contacts

made by different techniques such as printing, thermal evaporation, sputtering etc. and there

may be post preparation treatments in order to obtain near ideal Ohmic nature of contacts.

However, it has been observed that these contacts have particular range of current in which

Ohmic nature is sustained and outside this limits due to several reasons like high field effects

etc. the Ohmicity breaks. In the present case of ZnSe and ZnTe crystals grown by DVT

technique, a high conducting silver paste (Elteck-1228C-Bangalore) has been used. The well

cleaned crystals with good smooth flat surfaces have been selected by optical microscope and

on four corners of each of the sample four copper wires have been attached using the silver

paste. They have then been air dried at 50-600C. As mentioned earlier, all the samples have

213

then been tested for their Ohmic nature in order to find the linear range of I-V characteristics

to select a particular excitation current for Hall effect measurements. Such plots of typical

Current-Voltage (I-V) characteristics for ZnSe and ZnTe crystalline samples are shown in

figure 7.4 and 7.5 respectively, for set of contacts R12,12, R23,23 and R34,34, R41,41. From these

figures, it can be seen that the prepared samples of ZnSe and ZnTe possess Ohmic behavior

in the current range of fraction of microampere to few tens of microampere and do not

require further contact processing e.g. annealing etc.

214

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

ZnSe(R23,23)

Current

(A)

Voltage (V)

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

ZnSe(R12,12)Cur

rent (A)

Voltage (V)

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

ZnSe(R23,23)

Current

(A)

Voltage (V)

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

ZnSe(R23,23)

Current

(A)

Voltage (V)

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

ZnSe(R12,12)Cur

rent (A)

Voltage (V)-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

ZnSe(R12,12)Cur

rent (A)

Voltage (V)-5.E-07

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

5.E-07

-3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00

ZnSe (R34,34)

Current

(A)Voltage (V)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-2.00E+00 -1.00E+00 0.00E+00 1.00E+00 2.00E+00

ZnSe (R41,41)Cur

rent (A)

Voltage (V)

-5.E-07

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

5.E-07

-3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00

ZnSe (R34,34)

Current

(A)Voltage (V)-5.E-07

-4.E-07

-3.E-07

-2.E-07

-1.E-07

0.E+00

1.E-07

2.E-07

3.E-07

4.E-07

5.E-07

-3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00

ZnSe (R34,34)

Current

(A)Voltage (V)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-2.00E+00 -1.00E+00 0.00E+00 1.00E+00 2.00E+00

ZnSe (R41,41)Cur

rent (A)

Voltage (V)-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-2.00E+00 -1.00E+00 0.00E+00 1.00E+00 2.00E+00

ZnSe (R41,41)Cur

rent (A)

Voltage (V)

Figure 7.4 A set of typical I-V characteristics between R12,12, R23,23, R34,34 and R41,41

contacts on ZnSe crystal.

215

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

ZnTe (R23,23)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

ZnTe (R12,12)Cur

rent (A

)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

ZnTe (R23,23)

Curren

t (A)

Voltage (V)-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

ZnTe (R23,23)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

ZnTe (R12,12)Cur

rent (A

)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

ZnTe (R12,12)Cur

rent (A

)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-8.E-01 -6.E-01 -4.E-01 -2.E-01 0.E+00 2.E-01 4.E-01 6.E-01 8.E-01

ZnTe (R34,34)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-8.E-01 -6.E-01 -4.E-01 -2.E-01 0.E+00 2.E-01 4.E-01 6.E-01 8.E-01

ZnTe (R41,41)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-8.E-01 -6.E-01 -4.E-01 -2.E-01 0.E+00 2.E-01 4.E-01 6.E-01 8.E-01

ZnTe (R34,34)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-8.E-01 -6.E-01 -4.E-01 -2.E-01 0.E+00 2.E-01 4.E-01 6.E-01 8.E-01

ZnTe (R34,34)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-8.E-01 -6.E-01 -4.E-01 -2.E-01 0.E+00 2.E-01 4.E-01 6.E-01 8.E-01

ZnTe (R41,41)

Curren

t (A)

Voltage (V)

-3.E-05

-2.E-05

-1.E-05

0.E+00

1.E-05

2.E-05

3.E-05

-8.E-01 -6.E-01 -4.E-01 -2.E-01 0.E+00 2.E-01 4.E-01 6.E-01 8.E-01

ZnTe (R41,41)

Curren

t (A)

Voltage (V)

Figure 7.5 A set of typical I-V characteristics between R12,12, R23,23, R34,34 and R41,41

contacts on ZnTe crystal.

216

7.3.1.2 TEMPERATURE DEPENDENCE OF TRANSPORT PROPERTIES OFZnSe AND ZnTe CRYSTALS GROWN BY DVT TECHNIQUE

After confirmation of ohmic behavior of contacts on samples, Hall effect

measurements were carried out. Different operating typical conditions of the Hall

measurement system parameters and geometrical parameters of the samples are tabulated in

table 7.1 and 7.2 for ZnSe and ZnTe crystals respectively. Zero field resistivity and resistivity

at 3 kG magnetic field of ZnSe and ZnTe crystals at various temperatures (303K to 383K) are

shown in figures 7.6 and 7.7 respectively. It shows the effects of magnetic field as well as

temperature on resistivity for both types of crystals. There is a significant decrease in

resistivity, with both magnetic field and temperature for both the crystals of ZnSe and ZnTe.

This confirms the semiconducting behavior of the grown crystals. Various Hall parameters

like Hall coefficient, carrier density and mobility are measured for both the crystals at

magnetic field of 3 kG and at different temperatures (303K to 383K). The variations of these

parameters with temperature at magnetic field of 3 kG are shown in figures 7.8, 7.9 and 7.10

for ZnSe and ZnTe crystals. The positive sign of Hall coefficient variation with temperature

(Figure7.8) shows that the holes are the majority carrier which dominates the transport

properties in the entire temperature range of measurement. Carrier density and mobility

variations with temperature (Figure 7.9 and 7.10) display the fundamental property of

semiconductors that with increase in temperature more carriers are released from their bound

states and thereby increases the carrier density where as the thermal vibrations which are not

used in substantial release of charge carriers due to insufficient energy leads to the decrease

in the mobility.

217

A and BGeometry Selection

ONCurrent Reversal

2.0 sec.Dwell Time

HighResistance Range

Hall and Resistivity MeasurementMeasurement Type

1.5 KGField Step

+3.0 KGEnding Field

-3.0 KGStarting Field

Linear SweepField Profile

Measurement Parameters

OffDepletion Layer Correction

3.0 mmSample Length

1.0 mmSample Thickness

1.0Hall Factor

Van der PauwSample Type

ZnSe crystalSample

Sample parameters

A and BGeometry Selection

ONCurrent Reversal

2.0 sec.Dwell Time

HighResistance Range

Hall and Resistivity MeasurementMeasurement Type

1.5 KGField Step

+3.0 KGEnding Field

-3.0 KGStarting Field

Linear SweepField Profile

Measurement Parameters

OffDepletion Layer Correction

3.0 mmSample Length

1.0 mmSample Thickness

1.0Hall Factor

Van der PauwSample Type

ZnSe crystalSample

Sample parameters

Table 7.1 Sample and Hall measurement system parameters for ZnSe crystals.

218

A and BGeometry Selection

ONCurrent Reversal

2.0 sec.Dwell Time

HighResistance Range

Hall and Resistivity MeasurementMeasurement Type

1.0 KGField Step

+3.0 KGEnding Field

-3.0 KGStarting Field

Linear SweepField Profile

Measurement Parameters

OffDepletion Layer Correction

4.0 mmSample Length

1.5 mmSample Thickness

1.0Hall Factor

Van der PauwSample Type

ZnTe crystalSample

Sample parameters

A and BGeometry Selection

ONCurrent Reversal

2.0 sec.Dwell Time

HighResistance Range

Hall and Resistivity MeasurementMeasurement Type

1.0 KGField Step

+3.0 KGEnding Field

-3.0 KGStarting Field

Linear SweepField Profile

Measurement Parameters

OffDepletion Layer Correction

4.0 mmSample Length

1.5 mmSample Thickness

1.0Hall Factor

Van der PauwSample Type

ZnTe crystalSample

Sample parameters

Table 7.2 Sample and Hall measurement system parameters for ZnTe crystals.

219

0 .00E+00

5 .00E+01

1 .00E+02

1 .50E+02

2 .00E+02

2 .50E+02

3 .00E+02

300 320 340 360 380 400

Zn S e

Zn T e

Temperature (K)

Res

isti

vity

(.c

m)

0 .00E+00

5 .00E+01

1 .00E+02

1 .50E+02

2 .00E+02

2 .50E+02

3 .00E+02

300 320 340 360 380 400

Zn S e

Zn T e

Temperature (K)

Res

isti

vity

(.c

m)

0 .00E +00

2 .00E +01

4 .00E +01

6 .00E +01

8 .00E +01

1 .00E +02

1 .20E +02

1 .40E +02

300 320 340 360 380 400

Zn S e

Zn T e

Temperature (K)

Res

istiv

ity (

.cm

)

0 .00E +00

2 .00E +01

4 .00E +01

6 .00E +01

8 .00E +01

1 .00E +02

1 .20E +02

1 .40E +02

300 320 340 360 380 400

Zn S e

Zn T e

Temperature (K)

Res

istiv

ity (

.cm

)

Figure 7.6 Variation of zero field resistivity of ZnSe and ZnTe crystals with

temperature.

Figure 7.7 Variation of resistivity of ZnSe and ZnTe crystals at 3kG with

temperature.

220

0 .0 0 E +0 0

2 .0 0 E +1 8

4 .0 0 E +1 8

6 .0 0 E +1 8

8 .0 0 E +1 8

1 .0 0 E +1 9

1 .2 0 E +1 9

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0

Zn T e

Zn S e

Temperature (K)

Car

rier

Den

sity

(1/c

m3 )

0 .0 0 E +0 0

2 .0 0 E +1 8

4 .0 0 E +1 8

6 .0 0 E +1 8

8 .0 0 E +1 8

1 .0 0 E +1 9

1 .2 0 E +1 9

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0

Zn T e

Zn S e

Temperature (K)

Car

rier

Den

sity

(1/c

m3 )

0 .0 0 E +0 0

2 .0 0 E +0 1

4 .0 0 E +0 1

6 .0 0 E +0 1

8 .0 0 E +0 1

1 .0 0 E +0 2

1 .2 0 E +0 2

1 .4 0 E +0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0

Zn S e

Zn T e

Temperature (K)Hal

l Coe

ffic

ient

(cm3 /C

)

0 .0 0 E +0 0

2 .0 0 E +0 1

4 .0 0 E +0 1

6 .0 0 E +0 1

8 .0 0 E +0 1

1 .0 0 E +0 2

1 .2 0 E +0 2

1 .4 0 E +0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0

Zn S e

Zn T e

Temperature (K)Hal

l Coe

ffic

ient

(cm3 /C

)

Figure 7.8 Variation of Hall Coefficient of ZnSe and ZnTe crystals at 3kG with

temperature.

Figure 7.9 Variation of Carrier Density of ZnSe and ZnTe crystals at 3kG with

temperature.

221

0 .0 0 E + 0 0

1 .0 0 E + 0 2

2 .0 0 E + 0 2

3 .0 0 E + 0 2

4 .0 0 E + 0 2

5 .0 0 E + 0 2

6 .0 0 E + 0 2

7 .0 0 E + 0 2

8 .0 0 E + 0 2

9 .0 0 E + 0 2

1 .0 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0

Z n S e

Z n T e

Tem perature (K)

Mo

bili

ty [

cm2//(

VS

)]

0 .0 0 E + 0 0

1 .0 0 E + 0 2

2 .0 0 E + 0 2

3 .0 0 E + 0 2

4 .0 0 E + 0 2

5 .0 0 E + 0 2

6 .0 0 E + 0 2

7 .0 0 E + 0 2

8 .0 0 E + 0 2

9 .0 0 E + 0 2

1 .0 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0

Z n S e

Z n T e

Tem perature (K)

Mo

bili

ty [

cm2//(

VS

)]

Figure 7.10 Variation of Mobility of ZnSe and ZnTe crystals at 3kG with

temperature.

7.3.2 RESULTS OF ZnSe and ZnTe THIN FILMS DEPOSITED BYTHERMAL EVEPORATION TECHNIQUE

7.3.2.1 OHMIC CONTACTS TO THERMALLY EVAPORATED ZnSe AND ZnTeTHIN FILMS

Ohmic contacts to the deposited thin films of both ZnSe and ZnTe samples were

prepared by conducting silver paste as described above. Plots of I-V characteristics of ZnSe

thin films of various thicknesses deposited at different substrate temperatures are shown in

figure 7.11 and figure 7.12, while figures 7.13 and 7.14 represents I-V characteristics for

ZnTe thin films. From the figures 7.11 to 7.14, it can be seen that all contacts on prepared

samples possess Ohmic nature and they do not require any further contact treatment. It can be

observed that for all thin film samples the linear range of current extends only up to few

nano-amperes for ZnSe thin films and that up to few microamperes in case of ZnTe thin

films. This range is normally observed to be expanding by two to three orders of magnitude

for thicker films and for films that are deposited at elevated substrate temperatures in case of

both ZnSe and ZnTe thin films.

222

-1.E-09

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

1.E-09

-6.E+00 -5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 373K

Curre

nt (A)

Voltage (V)

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 303K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 303K

Curre

nt (A)

Voltage (V)

-2.5E-10

-2.0E-10

-1.5E-10

-1.0E-10

-5.0E-11

0.0E+00

5.0E-11

1.0E-10

1.5E-10

2.0E-10

2.5E-10

3.0E-10

-2.0E+01 -1.5E+01 -1.0E+01 -5.0E+00 0.0E+00 5.0E+00 1.0E+01 1.5E+01 2.0E+01

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 448K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00R12,12R23,23R34,34R41,41

ZnSe, 1000Å, 373K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 448K

Voltage (V)

Curre

nt (A)

-1.E-09

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

1.E-09

-6.E+00 -5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 373K

Curre

nt (A)

Voltage (V)-1.E-09

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

1.E-09

-6.E+00 -5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 373K

Curre

nt (A)

Voltage (V)

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 303K

Curre

nt (A)

Voltage (V)

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 303K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 303K

Curre

nt (A)

Voltage (V)

-2.5E-10

-2.0E-10

-1.5E-10

-1.0E-10

-5.0E-11

0.0E+00

5.0E-11

1.0E-10

1.5E-10

2.0E-10

2.5E-10

3.0E-10

-2.0E+01 -1.5E+01 -1.0E+01 -5.0E+00 0.0E+00 5.0E+00 1.0E+01 1.5E+01 2.0E+01

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 448K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00R12,12R23,23R34,34R41,41

ZnSe, 1000Å, 373K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 448K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 303K

Curre

nt (A)

Voltage (V)

-2.5E-10

-2.0E-10

-1.5E-10

-1.0E-10

-5.0E-11

0.0E+00

5.0E-11

1.0E-10

1.5E-10

2.0E-10

2.5E-10

3.0E-10

-2.0E+01 -1.5E+01 -1.0E+01 -5.0E+00 0.0E+00 5.0E+00 1.0E+01 1.5E+01 2.0E+01

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 448K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00R12,12R23,23R34,34R41,41

ZnSe, 1000Å, 373K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 303K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 303K

Curre

nt (A)

Voltage (V)

-2.5E-10

-2.0E-10

-1.5E-10

-1.0E-10

-5.0E-11

0.0E+00

5.0E-11

1.0E-10

1.5E-10

2.0E-10

2.5E-10

3.0E-10

-2.0E+01 -1.5E+01 -1.0E+01 -5.0E+00 0.0E+00 5.0E+00 1.0E+01 1.5E+01 2.0E+01

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 448K

Curre

nt (A)

Voltage (V)-2.5E-10

-2.0E-10

-1.5E-10

-1.0E-10

-5.0E-11

0.0E+00

5.0E-11

1.0E-10

1.5E-10

2.0E-10

2.5E-10

3.0E-10

-2.0E+01 -1.5E+01 -1.0E+01 -5.0E+00 0.0E+00 5.0E+00 1.0E+01 1.5E+01 2.0E+01

R12,12R23,23R34,34R41,41

ZnSe 1000Å, 448K

Curre

nt (A)

Voltage (V)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00R12,12R23,23R34,34R41,41

ZnSe, 1000Å, 373K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00R12,12R23,23R34,34R41,41

ZnSe, 1000Å, 373K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 448K

Voltage (V)

Curre

nt (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00R12,12R23,23R34,34R41,41

ZnSe, 2000Å, 448K

Voltage (V)

Curre

nt (A)

Figure 7.11 Plots of I-V characteristics for ZnSe thin films of 1000Å and 2000Ådeposited at various substrate temperatures.

223

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

-2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 303K

Voltage (V)

Curren

t (A)

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01

R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 373K

Voltage (V)

Curren

t (A)

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

-2.E+01 -2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01 2.E+01 2.E+01

R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 448K

Voltage (V)

Curren

t (A)

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

-2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 303K

Voltage (V)

Curren

t (A)

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

-2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 303K

Voltage (V)

Curren

t (A)

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01

R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 373K

Voltage (V)

Curren

t (A)

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01

R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 373K

Voltage (V)

Curren

t (A)

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

-2.E+01 -2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01 2.E+01 2.E+01

R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 448K

Voltage (V)

Curren

t (A)

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

-2.E+01 -2.E+01 -1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01 2.E+01 2.E+01

R12,12R23,23R34,34R41,41

ZnSe, 3000Å, 448K

Voltage (V)

Curren

t (A)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 303K

Curre

nt (A)

Voltage (V)

-1.E-09

-1.E-09

-1.E-09

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 373K

Curre

nt (A)

Voltage (V)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-6.E+00 -5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 448K

Curre

nt (A)

Voltage (V)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 303K

Curre

nt (A)

Voltage (V)-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 303K

Curre

nt (A)

Voltage (V)

-1.E-09

-1.E-09

-1.E-09

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 373K

Curre

nt (A)

Voltage (V)-1.E-09

-1.E-09

-1.E-09

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

-6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 373K

Curre

nt (A)

Voltage (V)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-6.E+00 -5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 448K

Curre

nt (A)

Voltage (V)-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-6.E+00 -5.E+00 -4.E+00 -3.E+00 -2.E+00 -1.E+00 0.E+00 1.E+00 2.E+00 3.E+00 4.E+00 5.E+00

R12,12R23,23R34,34R41,41

ZnSe, 5000Å, 448K

Curre

nt (A)

Voltage (V)

Figure 7.12 Plots of I-V characteristics for ZnSe thin films of 3000Å and 5000Ådeposited at various substrate temperatures.

224

-8.E-11

-6.E-11

-4.E-11

-2.E-11

0.E+00

2.E-11

4.E-11

6.E-11

8.E-11

1.E-10

1.E-10

-1.E+01 -8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00 1.E+01

R12,12R23,23R34,34R41,41

ZnTe, 1000Å, 448K

Voltage (V)

Curre

nt (A)

-6.E-07

-4.E-07

-2.E-07

0.E+00

2.E-07

4.E-07

6.E-07

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R34,34R41,41R23,23

ZnTe, 1000Å, 373K

Voltage (V)

Curre

nt(A)

-8.E-11

-6.E-11

-4.E-11

-2.E-11

0.E+00

2.E-11

4.E-11

6.E-11

8.E-11

1.E-10

-1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01 2.E+01

R12,12R23,23R34,34R41,41

ZnTe 1000Å, 303K

Voltage (V)

Curre

nt (A)

-8.E-11

-6.E-11

-4.E-11

-2.E-11

0.E+00

2.E-11

4.E-11

6.E-11

8.E-11

1.E-10

1.E-10

-1.E+01 -8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00 1.E+01

R12,12R23,23R34,34R41,41

ZnTe, 1000Å, 448K

Voltage (V)

Curre

nt (A)

-8.E-11

-6.E-11

-4.E-11

-2.E-11

0.E+00

2.E-11

4.E-11

6.E-11

8.E-11

1.E-10

1.E-10

-1.E+01 -8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00 1.E+01

R12,12R23,23R34,34R41,41

ZnTe, 1000Å, 448K

Voltage (V)

Curre

nt (A)

-6.E-07

-4.E-07

-2.E-07

0.E+00

2.E-07

4.E-07

6.E-07

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R34,34R41,41R23,23

ZnTe, 1000Å, 373K

Voltage (V)

Curre

nt(A)

-6.E-07

-4.E-07

-2.E-07

0.E+00

2.E-07

4.E-07

6.E-07

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R34,34R41,41R23,23

ZnTe, 1000Å, 373K

Voltage (V)

Curre

nt(A)

-8.E-11

-6.E-11

-4.E-11

-2.E-11

0.E+00

2.E-11

4.E-11

6.E-11

8.E-11

1.E-10

-1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01 2.E+01

R12,12R23,23R34,34R41,41

ZnTe 1000Å, 303K

Voltage (V)

Curre

nt (A)

-8.E-11

-6.E-11

-4.E-11

-2.E-11

0.E+00

2.E-11

4.E-11

6.E-11

8.E-11

1.E-10

-1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01 2.E+01

R12,12R23,23R34,34R41,41

ZnTe 1000Å, 303K

Voltage (V)

Curre

nt (A)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-6.E-02 -4.E-02 -2.E-02 0.E+00 2.E-02 4.E-02 6.E-02

R12,12R23,23R34,34R41,41

ZnTe, 2000Å, 303K

Voltage (V)

Curren

t (A)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-6.E-02 -4.E-02 -2.E-02 0.E+00 2.E-02 4.E-02 6.E-02

R12,12R23,23R34,34R41,41

ZnTe 2000Å, 373K

Curren

t (A)

Voltage (V)

-8.00E-09

-6.00E-09

-4.00E-09

-2.00E-09

0.00E+00

2.00E-09

4.00E-09

6.00E-09

8.00E-09

1.00E-08

-1.00E+01 -5.00E+00 0.00E+00 5.00E+00 1.00E+01 1.50E+01

R12,12R23,23R34,34R41,41

ZnTe 2000Å, 448K

Curren

t (A)

Voltage (V)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-6.E-02 -4.E-02 -2.E-02 0.E+00 2.E-02 4.E-02 6.E-02

R12,12R23,23R34,34R41,41

ZnTe, 2000Å, 303K

Voltage (V)

Curren

t (A)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-6.E-02 -4.E-02 -2.E-02 0.E+00 2.E-02 4.E-02 6.E-02

R12,12R23,23R34,34R41,41

ZnTe, 2000Å, 303K

Voltage (V)

Curren

t (A)

-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-6.E-02 -4.E-02 -2.E-02 0.E+00 2.E-02 4.E-02 6.E-02

R12,12R23,23R34,34R41,41

ZnTe 2000Å, 373K

Curren

t (A)

Voltage (V)-6.00E-07

-4.00E-07

-2.00E-07

0.00E+00

2.00E-07

4.00E-07

6.00E-07

-6.E-02 -4.E-02 -2.E-02 0.E+00 2.E-02 4.E-02 6.E-02

R12,12R23,23R34,34R41,41

ZnTe 2000Å, 373K

Curren

t (A)

Voltage (V)

-8.00E-09

-6.00E-09

-4.00E-09

-2.00E-09

0.00E+00

2.00E-09

4.00E-09

6.00E-09

8.00E-09

1.00E-08

-1.00E+01 -5.00E+00 0.00E+00 5.00E+00 1.00E+01 1.50E+01

R12,12R23,23R34,34R41,41

ZnTe 2000Å, 448K

Curren

t (A)

Voltage (V)

-8.00E-09

-6.00E-09

-4.00E-09

-2.00E-09

0.00E+00

2.00E-09

4.00E-09

6.00E-09

8.00E-09

1.00E-08

-1.00E+01 -5.00E+00 0.00E+00 5.00E+00 1.00E+01 1.50E+01

R12,12R23,23R34,34R41,41

ZnTe 2000Å, 448K

Curren

t (A)

Voltage (V)

Figure 7.13 Plots of I-V characteristics for ZnTe thin films of 1000Å and 2000Ådeposited at various substrate temperatures.

225

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 303K

Voltage (V)

Curre

nt (A)

-2.E-09

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

2.E-09

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 373K

Voltage (V)

Curre

nt (A)

-5.E-07

-4.E-07-3.E-07

-2.E-07

-1.E-070.E+00

1.E-072.E-07

3.E-07

4.E-075.E-07

6.E-07

-3.E-01 -2.E-01 -1.E-01 0.E+00 1.E-01 2.E-01 3.E-01

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 448K

Voltage (V)

Curre

nt (A)

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 303K

Voltage (V)

Curre

nt (A)

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 303K

Voltage (V)

Curre

nt (A)

-2.E-09

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

2.E-09

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 373K

Voltage (V)

Curre

nt (A)

-2.E-09

-2.E-09

-1.E-09

-5.E-10

0.E+00

5.E-10

1.E-09

2.E-09

2.E-09

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00 8.E+00

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 373K

Voltage (V)

Curre

nt (A)

-5.E-07

-4.E-07-3.E-07

-2.E-07

-1.E-070.E+00

1.E-072.E-07

3.E-07

4.E-075.E-07

6.E-07

-3.E-01 -2.E-01 -1.E-01 0.E+00 1.E-01 2.E-01 3.E-01

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 448K

Voltage (V)

Curre

nt (A)

-5.E-07

-4.E-07-3.E-07

-2.E-07

-1.E-070.E+00

1.E-072.E-07

3.E-07

4.E-075.E-07

6.E-07

-3.E-01 -2.E-01 -1.E-01 0.E+00 1.E-01 2.E-01 3.E-01

R12,12R23,23R34,34R41,41

ZnTe, 3000Å, 448K

Voltage (V)

Curre

nt (A)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00R12,12R23,23R34,34R41,41

ZnTe, 5000Å, 303K

Voltage (V)

Curren

t (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01R12,12R23,23R34,34R41,41

ZnTe, 5000Å, 373K

Voltage (V)

Curren

t (A)

-6.E-07

-4.E-07

-2.E-07

0.E+00

2.E-07

4.E-07

6.E-07

-4.E-01 -3.E-01 -2.E-01 -1.E-01 0.E+00 1.E-01 2.E-01 3.E-01 4.E-01

R12,12R23,2334,34R41,41

ZnTe, 5000Å, 448K

Voltage (V)

Curren

t (A)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00R12,12R23,23R34,34R41,41

ZnTe, 5000Å, 303K

Voltage (V)

Curren

t (A)

-5.E-10

-4.E-10

-3.E-10

-2.E-10

-1.E-10

0.E+00

1.E-10

2.E-10

3.E-10

4.E-10

5.E-10

-8.E+00 -6.E+00 -4.E+00 -2.E+00 0.E+00 2.E+00 4.E+00 6.E+00R12,12R23,23R34,34R41,41

ZnTe, 5000Å, 303K

Voltage (V)

Curren

t (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01R12,12R23,23R34,34R41,41

ZnTe, 5000Å, 373K

Voltage (V)

Curren

t (A)

-8.E-10

-6.E-10

-4.E-10

-2.E-10

0.E+00

2.E-10

4.E-10

6.E-10

8.E-10

-1.E+01 -5.E+00 0.E+00 5.E+00 1.E+01R12,12R23,23R34,34R41,41

ZnTe, 5000Å, 373K

Voltage (V)

Curren

t (A)

-6.E-07

-4.E-07

-2.E-07

0.E+00

2.E-07

4.E-07

6.E-07

-4.E-01 -3.E-01 -2.E-01 -1.E-01 0.E+00 1.E-01 2.E-01 3.E-01 4.E-01

R12,12R23,2334,34R41,41

ZnTe, 5000Å, 448K

Voltage (V)

Curren

t (A)

-6.E-07

-4.E-07

-2.E-07

0.E+00

2.E-07

4.E-07

6.E-07

-4.E-01 -3.E-01 -2.E-01 -1.E-01 0.E+00 1.E-01 2.E-01 3.E-01 4.E-01

R12,12R23,2334,34R41,41

ZnTe, 5000Å, 448K

Voltage (V)

Curren

t (A)

Figure 7.14 Plots of I-V characteristics for ZnTe thin films of 3000Å and 5000Ådeposited at different substrate temperatures.

226

7.3.2.2 TRANSPORT PROPERTIES OF ZnSe THIN FILMS

In present study, the van der Pauw method has been used. Various measurement

parameters like current forced, magnetic field, contact geometry, current reversal field

reversal with the step of field, zero field resistivity etc. were set using software. After proper

setting of these parameters the sample assembled on the sample holder placed between the

pole magnets, undergo the execution of the Hall measurement process. The Ohmic contacts

to the samples placed under Hall measurement system were confirmed by simply measuring

their current voltage characteristics as described above.

7.3.2.2 .1 THICKNESS DEPENDENT TRANSPORT PROPERTIES

Figures 7.15 to 7.19 show the variation of zero field resistivity, resistivity at 3kG,

Hall coefficient, carrier density and mobility with thickness of ZnSe thin films deposited at

different substrate temperatures when measured over the temperature range 303-393 K.

Following observations can be easily made from these figures

1. Resistivity of all thin film samples decreases with increasing thickness. This may be

because of the fact that thicker films are normally continuous having large number of

bigger oriented grains. This growth tendency is enhanced at elevated substrate

temperatures as reflected by the decreasing resistivity values shown in the figures

7.15 and 7.16.

2. The sign of the Hall coefficient remains positive for all the samples of ZnSe thin

films and its magnitude remains in the range of 12-1.49x104 cm3C-1(Fig.7.17). This

indicates that all the prepared films possess holes as a majority charge carrier and thus

all the films exhibit p-type semiconducting nature. Also the majority carrier type

reversal is not observed in the studied range of temperature i.e.303-393K. It is further

found that the magnitude of Hall coefficient decreases monotonically with the

increase in film thickness as well as the substrate temperature.

3. Majority charge carrier density i.e. hole density in case of all the deposited thin films

of ZnSe increases with the thickness of the films up to 1.4x1017cm-3 as shown in the

figure 7.18.

4. Charge carrier mobility for all the deposited thin films of ZnSe decreases with

increasing film thickness(Fig.7.19)

227

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(c) Ts = 448K

0 .0 E+0 0

1 .0 E+0 2

2 .0 E+0 2

3 .0 E+0 2

4 .0 E+0 2

5 .0 E+0 2

6 .0 E+0 2

7 .0 E+0 2

8 .0 E+0 2

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(a) Ts = 303K

0.0E+005.0E+011.0E+021.5E+022.0E+022.5E+023.0E+023.5E+024.0E+024.5E+025.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(b) Ts = 373K

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(c) Ts = 448K

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(c) Ts = 448K

0 .0 E+0 0

1 .0 E+0 2

2 .0 E+0 2

3 .0 E+0 2

4 .0 E+0 2

5 .0 E+0 2

6 .0 E+0 2

7 .0 E+0 2

8 .0 E+0 2

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(a) Ts = 303K

0 .0 E+0 0

1 .0 E+0 2

2 .0 E+0 2

3 .0 E+0 2

4 .0 E+0 2

5 .0 E+0 2

6 .0 E+0 2

7 .0 E+0 2

8 .0 E+0 2

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(a) Ts = 303K

0.0E+005.0E+011.0E+021.5E+022.0E+022.5E+023.0E+023.5E+024.0E+024.5E+025.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(b) Ts = 373K

0.0E+005.0E+011.0E+021.5E+022.0E+022.5E+023.0E+023.5E+024.0E+024.5E+025.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

Film Thickness (kÅ)

Res

isti

vity(

cm)

(b) Ts = 373K

Figure 7.15 Variation of zero field resistivity of ZnSe thin films deposited at different

substrate temperatures with film thickness.

228

0.0E+00

1.0E+02

2.0E+02

3.0E+02

4.0E+02

5.0E+02

6.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(a) Ts = 303K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

2.5E+02

3.0E+02

3.5E+02

4.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b) Ts = 373K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

2.5E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(c) Ts = 448K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

1.0E+02

2.0E+02

3.0E+02

4.0E+02

5.0E+02

6.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(a) Ts = 303K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

1.0E+02

2.0E+02

3.0E+02

4.0E+02

5.0E+02

6.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(a) Ts = 303K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

2.5E+02

3.0E+02

3.5E+02

4.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b) Ts = 373K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

2.5E+02

3.0E+02

3.5E+02

4.0E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b) Ts = 373K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

2.5E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(c) Ts = 448K

Film Thickness (kÅ)

Res

isti

vity(

cm)

0.0E+00

5.0E+01

1.0E+02

1.5E+02

2.0E+02

2.5E+02

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(c) Ts = 448K

Film Thickness (kÅ)

Res

isti

vity(

cm)

Figure 7.16 Variation of resistivity (3kG) of ZnSe thin films deposited at different

substrate temperatures with films thickness.

229

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

1 .6 E + 0 4

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E +0 0

2 .0 E +0 2

4 .0 E +0 2

6 .0 E +0 2

8 .0 E +0 2

1 .0 E +0 3

1 .2 E +0 3

1 .4 E +0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 4 4 8 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

1 .6 E + 0 4

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

1 .6 E + 0 4

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E +0 0

2 .0 E +0 2

4 .0 E +0 2

6 .0 E +0 2

8 .0 E +0 2

1 .0 E +0 3

1 .2 E +0 3

1 .4 E +0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 4 4 8 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E +0 0

2 .0 E +0 2

4 .0 E +0 2

6 .0 E +0 2

8 .0 E +0 2

1 .0 E +0 3

1 .2 E +0 3

1 .4 E +0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 4 4 8 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

F ilm T h ick n e s s (k Å )

Hal

l Co

effi

cien

t (c

m3 /

C)

Figure 7.17 Variation of Hall Coefficient for ZnSe thin films deposited at various

substrate temperatures with films thickness.

230

0.0E+00

1.0E+16

2.0E+16

3.0E+16

4.0E+16

5.0E+16

6.0E+16

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(a) T s = 303K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

0.0E+00

2.0E+16

4.0E+16

6.0E+16

8.0E+16

1.0E+17

1.2E+17

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b ) T s = 373K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

0.0E+00

2.0E+16

4.0E+16

6.0E+16

8.0E+16

1.0E+17

1.2E+17

1.4E+17

1.6E+17

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

(c ) T s = 448K

0.0E+00

1.0E+16

2.0E+16

3.0E+16

4.0E+16

5.0E+16

6.0E+16

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(a) T s = 303K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

0.0E+00

1.0E+16

2.0E+16

3.0E+16

4.0E+16

5.0E+16

6.0E+16

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(a) T s = 303K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

0.0E+00

2.0E+16

4.0E+16

6.0E+16

8.0E+16

1.0E+17

1.2E+17

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b ) T s = 373K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

0.0E+00

2.0E+16

4.0E+16

6.0E+16

8.0E+16

1.0E+17

1.2E+17

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b ) T s = 373K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

0.0E+00

2.0E+16

4.0E+16

6.0E+16

8.0E+16

1.0E+17

1.2E+17

1.4E+17

1.6E+17

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

(c ) T s = 448K

0.0E+00

2.0E+16

4.0E+16

6.0E+16

8.0E+16

1.0E+17

1.2E+17

1.4E+17

1.6E+17

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

Film T h ickness (kÅ)

Car

rier

Den

sity

(cm-3)

(c ) T s = 448K

Figure 7.18 Variation of Carrier Density of ZnSe thin films deposited at various

substrate temperatures with films thickness.

231

0 .0 E + 0 0

1 .0 E + 0 3

2 .0 E + 0 3

3 .0 E + 0 3

4 .0 E + 0 3

5 .0 E + 0 3

6 .0 E + 0 3

7 .0 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a) Ts = 303K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 .0 E + 0 0

5 .0 E + 0 2

1 .0 E + 0 3

1 .5 E + 0 3

2 .0 E + 0 3

2 .5 E + 0 3

3 .0 E + 0 3

3 .5 E + 0 3

4 .0 E + 0 3

4 .5 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b) Ts = 373K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 . 0 0 E + 0 0

2 . 0 0 E + 0 2

4 . 0 0 E + 0 2

6 . 0 0 E + 0 2

8 . 0 0 E + 0 2

1 . 0 0 E + 0 3

1 . 2 0 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c) Ts = 448K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 .0 E + 0 0

1 .0 E + 0 3

2 .0 E + 0 3

3 .0 E + 0 3

4 .0 E + 0 3

5 .0 E + 0 3

6 .0 E + 0 3

7 .0 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a) Ts = 303K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 .0 E + 0 0

1 .0 E + 0 3

2 .0 E + 0 3

3 .0 E + 0 3

4 .0 E + 0 3

5 .0 E + 0 3

6 .0 E + 0 3

7 .0 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a) Ts = 303K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 .0 E + 0 0

5 .0 E + 0 2

1 .0 E + 0 3

1 .5 E + 0 3

2 .0 E + 0 3

2 .5 E + 0 3

3 .0 E + 0 3

3 .5 E + 0 3

4 .0 E + 0 3

4 .5 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b) Ts = 373K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 .0 E + 0 0

5 .0 E + 0 2

1 .0 E + 0 3

1 .5 E + 0 3

2 .0 E + 0 3

2 .5 E + 0 3

3 .0 E + 0 3

3 .5 E + 0 3

4 .0 E + 0 3

4 .5 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b) Ts = 373K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 . 0 0 E + 0 0

2 . 0 0 E + 0 2

4 . 0 0 E + 0 2

6 . 0 0 E + 0 2

8 . 0 0 E + 0 2

1 . 0 0 E + 0 3

1 . 2 0 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c) Ts = 448K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

0 . 0 0 E + 0 0

2 . 0 0 E + 0 2

4 . 0 0 E + 0 2

6 . 0 0 E + 0 2

8 . 0 0 E + 0 2

1 . 0 0 E + 0 3

1 . 2 0 E + 0 3

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c) Ts = 448K

Film Thickness (kÅ)

Mob

ility

[cm2 /

(VS

)]

Figure 7.19 Variation of Mobility of ZnSe thin films deposited at various substrate

temperatures with films thickness.

232

7.3.2.2.2 SUBSTRATE TEMPERATURE DEPENDENT TRANSPORT

PROPERTIES

Variation of various Hall effect parameters like resistivity, Hall coefficient, carrier density

and mobility of ZnSe thin films with the film thickness has been studied. Figures 7.20 to 7.24

show the variation of zero field resistivity, resistivity at 3kG, Hall coefficient, carrier density

and mobility with substrate temperature for ZnSe thin films of different thickness when

measured over the temperature range 303-393 K. Following observations can be easily made

from these figures

1. Resistivity of all thin film samples decreases with increasing substrate temperatureas

shown in the figures 7.20 and 7.21. This is because of the decrease of the lattice strain

value that causes an improvement in crystallinity of the films deposited at higher

substrate temperatures [20]. At the lower substrate temperatures, deposited films

will have smaller grain sizes with larger grain boundaries which are highly distorted

and thus they have large number of defect states. Therefore the films deposited at

higher substrate temperatures will have comparatively larger grain sizes which can

cause decrease in the defect states and thereby leads toincrease the conductivity of the

films [39-41].

2. The values of Hall coefficient and carrier mobility decreases with the increase in

substrate temperature as shown in figure7.22 and 7.24.

3. Majority charge carrier density i.e. hole density in case of all the deposited thin films

of ZnSe increases with the substrate temperature of the films up to 1.4x1017cm-3 as

shown in the figure 7.23.

233

0 . 0 0 E + 0 0

1 . 0 0 E + 0 2

2 . 0 0 E + 0 2

3 . 0 0 E + 0 2

4 . 0 0 E + 0 2

5 . 0 0 E + 0 2

6 . 0 0 E + 0 2

7 . 0 0 E + 0 2

8 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sist

ivit

y (

Ωc

m)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 2

2 . 0 0 E + 0 2

3 . 0 0 E + 0 2

4 . 0 0 E + 0 2

5 . 0 0 E + 0 2

6 . 0 0 E + 0 2

7 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 2

2 . 0 0 E + 0 2

3 . 0 0 E + 0 2

4 . 0 0 E + 0 2

5 . 0 0 E + 0 2

6 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 0 E + 0 0

5 . 0 0 E + 0 1

1 . 0 0 E + 0 2

1 . 5 0 E + 0 2

2 . 0 0 E + 0 2

2 . 5 0 E + 0 2

3 . 0 0 E + 0 2

3 . 5 0 E + 0 2

4 . 0 0 E + 0 2

4 . 5 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 2

2 . 0 0 E + 0 2

3 . 0 0 E + 0 2

4 . 0 0 E + 0 2

5 . 0 0 E + 0 2

6 . 0 0 E + 0 2

7 . 0 0 E + 0 2

8 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sist

ivit

y (

Ωc

m)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 2

2 . 0 0 E + 0 2

3 . 0 0 E + 0 2

4 . 0 0 E + 0 2

5 . 0 0 E + 0 2

6 . 0 0 E + 0 2

7 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 2

2 . 0 0 E + 0 2

3 . 0 0 E + 0 2

4 . 0 0 E + 0 2

5 . 0 0 E + 0 2

6 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 0 E + 0 0

5 . 0 0 E + 0 1

1 . 0 0 E + 0 2

1 . 5 0 E + 0 2

2 . 0 0 E + 0 2

2 . 5 0 E + 0 2

3 . 0 0 E + 0 2

3 . 5 0 E + 0 2

4 . 0 0 E + 0 2

4 . 5 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Ǻ

Figure 7.20 Variation of zero field resistivity for ZnSe thin films of different

thicknesses with their substrate temperature.

234

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sist

ivit

y (

Ωc

m)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 0 E + 0 0

5 . 0 0 E + 0 1

1 . 0 0 E + 0 2

1 . 5 0 E + 0 2

2 . 0 0 E + 0 2

2 . 5 0 E + 0 2

3 . 0 0 E + 0 2

3 . 5 0 E + 0 2

4 . 0 0 E + 0 2

4 . 5 0 E + 0 2

5 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

4 . 5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( d ) T = 5 k Ǻ

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sist

ivit

y (

Ωc

m)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 0 E + 0 0

5 . 0 0 E + 0 1

1 . 0 0 E + 0 2

1 . 5 0 E + 0 2

2 . 0 0 E + 0 2

2 . 5 0 E + 0 2

3 . 0 0 E + 0 2

3 . 5 0 E + 0 2

4 . 0 0 E + 0 2

4 . 5 0 E + 0 2

5 . 0 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K

3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

4 . 5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(Ω

cm

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( d ) T = 5 k Ǻ

Figure 7.21 Variation of resistivity (3kG) for ZnSe thin films of different thicknesses

with their substrate temperature.

235

0 . 0 E + 0 0

2 . 0 E + 0 3

4 . 0 E + 0 3

6 . 0 E + 0 3

8 . 0 E + 0 3

1 . 0 E + 0 4

1 . 2 E + 0 4

1 . 4 E + 0 4

1 . 6 E + 0 4

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 0 3

4 . 0 E + 0 3

6 . 0 E + 0 3

8 . 0 E + 0 3

1 . 0 E + 0 4

1 . 2 E + 0 4

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 3

2 . 0 0 E + 0 3

3 . 0 0 E + 0 3

4 . 0 0 E + 0 3

5 . 0 0 E + 0 3

6 . 0 0 E + 0 3

7 . 0 0 E + 0 3

8 . 0 0 E + 0 3

9 . 0 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 E + 0 0

5 . 0 E + 0 2

1 . 0 E + 0 3

1 . 5 E + 0 3

2 . 0 E + 0 3

2 . 5 E + 0 3

3 . 0 E + 0 3

3 . 5 E + 0 3

4 . 0 E + 0 3

4 . 5 E + 0 3

5 . 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( d ) T = 5 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 0 3

4 . 0 E + 0 3

6 . 0 E + 0 3

8 . 0 E + 0 3

1 . 0 E + 0 4

1 . 2 E + 0 4

1 . 4 E + 0 4

1 . 6 E + 0 4

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 0 3

4 . 0 E + 0 3

6 . 0 E + 0 3

8 . 0 E + 0 3

1 . 0 E + 0 4

1 . 2 E + 0 4

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 0 E + 0 0

1 . 0 0 E + 0 3

2 . 0 0 E + 0 3

3 . 0 0 E + 0 3

4 . 0 0 E + 0 3

5 . 0 0 E + 0 3

6 . 0 0 E + 0 3

7 . 0 0 E + 0 3

8 . 0 0 E + 0 3

9 . 0 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 E + 0 0

5 . 0 E + 0 2

1 . 0 E + 0 3

1 . 5 E + 0 3

2 . 0 E + 0 3

2 . 5 E + 0 3

3 . 0 E + 0 3

3 . 5 E + 0 3

4 . 0 E + 0 3

4 . 5 E + 0 3

5 . 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 / C

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( d ) T = 5 k Ǻ

Figure 7.22 Variation of Hall Coefficient for ZnSe thin films of different thicknesses

with their substrate temperature.

236

0 .0 E + 0 0

1 .0 E + 1 6

2 .0 E + 1 6

3 .0 E + 1 6

4 .0 E + 1 6

5 .0 E + 1 6

6 .0 E + 1 6

7 .0 E + 1 6

8 .0 E + 1 6

9 .0 E + 1 6

1 .0 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

nsi

ty (

cm

- 3)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 1 6

4 . 0 E + 1 6

6 . 0 E + 1 6

8 . 0 E + 1 6

1 . 0 E + 1 7

1 . 2 E + 1 7

1 . 4 E + 1 7

1 . 6 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

ns

ity

(c

m- 3

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 1 6

4 . 0 E + 1 6

6 . 0 E + 1 6

8 . 0 E + 1 6

1 . 0 E + 1 7

1 . 2 E + 1 7

1 . 4 E + 1 7

1 . 6 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

ns

ity

(c

m- 3

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 1 6

4 . 0 E + 1 6

6 . 0 E + 1 6

8 . 0 E + 1 6

1 . 0 E + 1 7

1 . 2 E + 1 7

1 . 4 E + 1 7

1 . 6 E + 1 7

1 . 8 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

ns

ity

(c

m- 3

)

3 0 3 K

3 1 3 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( d ) T = 5 k Ǻ

0 .0 E + 0 0

1 .0 E + 1 6

2 .0 E + 1 6

3 .0 E + 1 6

4 .0 E + 1 6

5 .0 E + 1 6

6 .0 E + 1 6

7 .0 E + 1 6

8 .0 E + 1 6

9 .0 E + 1 6

1 .0 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

nsi

ty (

cm

- 3)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( a ) T = 1 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 1 6

4 . 0 E + 1 6

6 . 0 E + 1 6

8 . 0 E + 1 6

1 . 0 E + 1 7

1 . 2 E + 1 7

1 . 4 E + 1 7

1 . 6 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

ns

ity

(c

m- 3

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( b ) T = 2 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 1 6

4 . 0 E + 1 6

6 . 0 E + 1 6

8 . 0 E + 1 6

1 . 0 E + 1 7

1 . 2 E + 1 7

1 . 4 E + 1 7

1 . 6 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

ns

ity

(c

m- 3

)

3 0 3 K

3 1 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( c ) T = 3 k Ǻ

0 . 0 E + 0 0

2 . 0 E + 1 6

4 . 0 E + 1 6

6 . 0 E + 1 6

8 . 0 E + 1 6

1 . 0 E + 1 7

1 . 2 E + 1 7

1 . 4 E + 1 7

1 . 6 E + 1 7

1 . 8 E + 1 7

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rr

ier

De

ns

ity

(c

m- 3

)

3 0 3 K

3 1 3 3 K

3 2 3 K

3 3 3 K

3 4 3 K

3 5 3 K

3 6 3 K

3 7 3 K

3 8 3 K

3 9 3 K

( d ) T = 5 k Ǻ

Figure 7.23 Variation of Carrier Density for ZnSe thin films of different thickness

with their substrate temperature.

237

Figure 7.24 Variation of Mobility for ZnSe thin films of different thicknesses with

their substrate temperature.

238

0.0E+00

1.0E+02

2.0E+02

3.0E+02

4.0E+02

5.0E+02

6.0E+02

7.0E+02

8.0E+02

300 310 320 330 340 350 360 370 380 390 400

Temperature (K)

Resis

tivity

(Ωcm

)

1KA2KA3KA5KA

(a) Ts = 303 K

7.3.2.2 .3 TEMPERATURE DEPENDENT TRANSPORT PROPERTIES

Hall parameters have been measured at various temperatures from 303K to 393K.

Figure 7.25(a),(b),(c) to figure 7.29 shows the variation of different Hall parameters with the

temperatures for ZnSe thin films of different thicknesses deposited at different substrate

temperatures. It can be seen from figure 7.25(a),(b),(c) and 7.26 that as the temperature

increase, films become more conductive and resistivity decreases due to increase in grain size

and reduction in defects as discussed above. Similarly, Hall coefficient and mobility

decreases with temperature and carrier density increases with temperature.

Figure 7.25 (a) Temperature variation of zero field resistivity for ZnSe thin films

of various thicknesses deposited at 303K.

239

0.00E+00

5.00E+01

1.00E+02

1.50E+02

2.00E+02

2.50E+02

3.00E+02

3.50E+02

4.00E+02

4.50E+02

5.00E+02

300 310 320 330 340 350 360 370 380 390 400

Temperature (K)

Res

istiv

ity (Ω

cm) 1KA

2KA3KA5KA

(b) Ts = 373 K

0.00E+00

5.00E+01

1.00E+02

1.50E+02

2.00E+02

2.50E+02

3.00E+02

3.50E+02

300 310 320 330 340 350 360 370 380 390 400

Temperature (K)

Res

istiv

ity (Ω

cm) 1KA

2KA3KA5KA

(c) Ts = 448 K

0.00E+00

5.00E+01

1.00E+02

1.50E+02

2.00E+02

2.50E+02

3.00E+02

3.50E+02

4.00E+02

4.50E+02

5.00E+02

300 310 320 330 340 350 360 370 380 390 400

Temperature (K)

Res

istiv

ity (Ω

cm) 1KA

2KA3KA5KA

(b) Ts = 373 K

0.00E+00

5.00E+01

1.00E+02

1.50E+02

2.00E+02

2.50E+02

3.00E+02

3.50E+02

300 310 320 330 340 350 360 370 380 390 400

Temperature (K)

Res

istiv

ity (Ω

cm) 1KA

2KA3KA5KA

(c) Ts = 448 K

Figure 7.25 (b),(c) Temperature variation of zero field resistivity for ZnSe thin films

of various thicknesses deposited at 373K and 448K

240

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e r a tu r e (K )

Res

isti

vit

y (

Ωcm

) 1 K A2 K A3 K A5 K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

4 .0 E + 0 2

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e ra tu re (K )

Res

isti

vit

y (

Ωcm

) 1 K A2 K A3 K A5 K A

(b ) T s = 3 7 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e r a tu r e (K )

Res

isti

vit

y (

Ωcm

) 1 K A2 K A3 K A5 K A

(C ) T s = 4 4 8 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e r a tu r e (K )

Res

isti

vit

y (

Ωcm

) 1 K A2 K A3 K A5 K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

4 .0 E + 0 2

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e ra tu re (K )

Res

isti

vit

y (

Ωcm

) 1 K A2 K A3 K A5 K A

(b ) T s = 3 7 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e r a tu r e (K )

Res

isti

vit

y (

Ωcm

) 1 K A2 K A3 K A5 K A

(C ) T s = 4 4 8 K

Figure 7.26 Temperature variation of resistivity (3kG) for ZnSe thin films of various

thicknesses deposited at different substrate temperatures.

241

0 .0 E +0 0

2 .0 E +0 3

4 .0 E +0 3

6 .0 E +0 3

8 .0 E +0 3

1 .0 E +0 4

1 .2 E +0 4

1 .4 E +0 4

1 .6 E +0 4

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e mpe ra ture (K)

Hal

l Coe

ffic

ien

t (c

m3 /C

) 1K A2K A3K A5K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Ha

ll C

oe

ffic

ien

t (c

m3 /C

)

1 K A2 K A3 K A5 K A

(b ) T s = 3 7 3 K

0 .0 0 E + 0 0

2 .0 0 E + 0 2

4 .0 0 E + 0 2

6 .0 0 E + 0 2

8 .0 0 E + 0 2

1 .0 0 E + 0 3

1 .2 0 E + 0 3

1 .4 0 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e ra tu re (K )

Ha

ll C

oef

fici

ent

(cm

3 /C) 1 K A

2 K A3 K A5 K A

(C ) T s = 4 4 8 K

0 .0 E +0 0

2 .0 E +0 3

4 .0 E +0 3

6 .0 E +0 3

8 .0 E +0 3

1 .0 E +0 4

1 .2 E +0 4

1 .4 E +0 4

1 .6 E +0 4

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e mpe ra ture (K)

Hal

l Coe

ffic

ien

t (c

m3 /C

) 1K A2K A3K A5K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

2 .0 E + 0 3

4 .0 E + 0 3

6 .0 E + 0 3

8 .0 E + 0 3

1 .0 E + 0 4

1 .2 E + 0 4

1 .4 E + 0 4

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Ha

ll C

oe

ffic

ien

t (c

m3 /C

)

1 K A2 K A3 K A5 K A

(b ) T s = 3 7 3 K

0 .0 0 E + 0 0

2 .0 0 E + 0 2

4 .0 0 E + 0 2

6 .0 0 E + 0 2

8 .0 0 E + 0 2

1 .0 0 E + 0 3

1 .2 0 E + 0 3

1 .4 0 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e ra tu re (K )

Ha

ll C

oef

fici

ent

(cm

3 /C) 1 K A

2 K A3 K A5 K A

(C ) T s = 4 4 8 K

Figure 7.27 Temperature variation of Hall coefficient for ZnSe thin films of various

thicknesses deposited at various substrate temperatures.

242

0 .0 E +0 0

1 .0 E +1 6

2 .0 E +1 6

3 .0 E +1 6

4 .0 E +1 6

5 .0 E +1 6

6 .0 E +1 6

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T em pera ture (K )

Car

rier

Den

sity

(cm-3)

1K A2K A3K A5K A

(a) Ts = 303 K

0 .0 E + 0 0

2 .0 E + 1 6

4 .0 E + 1 6

6 .0 E + 1 6

8 .0 E + 1 6

1 .0 E + 1 7

1 .2 E + 1 7

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e r a tu r e (K )

Ca

rrie

r D

ensi

ty (

cm-3

)

1 K A2 K A3 K A5 K A

(b ) T s = 3 7 3 K

0 .0 E + 0 0

5 .0 E + 1 6

1 .0 E + 1 7

1 .5 E + 1 7

2 .0 E + 1 7

2 .5 E + 1 7

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T em p era tu re (K )

Car

rier

Den

sity

(cm

-3)

1 K A2 K A3 K A5 K A

(C ) Ts = 4 4 8 K

0 .0 E +0 0

1 .0 E +1 6

2 .0 E +1 6

3 .0 E +1 6

4 .0 E +1 6

5 .0 E +1 6

6 .0 E +1 6

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T em pera ture (K )

Car

rier

Den

sity

(cm-3)

1K A2K A3K A5K A

(a) Ts = 303 K

0 .0 E + 0 0

2 .0 E + 1 6

4 .0 E + 1 6

6 .0 E + 1 6

8 .0 E + 1 6

1 .0 E + 1 7

1 .2 E + 1 7

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m p e r a tu r e (K )

Ca

rrie

r D

ensi

ty (

cm-3

)

1 K A2 K A3 K A5 K A

(b ) T s = 3 7 3 K

0 .0 E + 0 0

5 .0 E + 1 6

1 .0 E + 1 7

1 .5 E + 1 7

2 .0 E + 1 7

2 .5 E + 1 7

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T em p era tu re (K )

Car

rier

Den

sity

(cm

-3)

1 K A2 K A3 K A5 K A

(C ) Ts = 4 4 8 K

Figure 7.28 Temperature variation of Carrier Density for ZnSe thin films of various

thicknesses deposited at various substrate temperatures.

243

0 .0 E + 0 0

1 .0 E + 0 3

2 .0 E + 0 3

3 .0 E + 0 3

4 .0 E + 0 3

5 .0 E + 0 3

6 .0 E + 0 3

7 .0 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m pe ra ture (K )

Mob

ility

(cm2 /V

S) 1K A

2K A3K A5K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

5 .0 E + 0 2

1 .0 E + 0 3

1 .5 E + 0 3

2 .0 E + 0 3

2 .5 E + 0 3

3 .0 E + 0 3

3 .5 E + 0 3

4 .0 E + 0 3

4 .5 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m pe ra ture (K )

Mob

ility

(cm2 /V

S) 1K A

2K A3K A5K A

(b) T s = 3 7 3 K

0 .0 E + 0 0

2 .0 E + 0 2

4 .0 E + 0 2

6 .0 E + 0 2

8 .0 E + 0 2

1 .0 E + 0 3

1 .2 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m pe ra ture (K )

Mob

ility

(cm2 /V

S) 1K A

2K A3K A5K A

(C ) T s = 4 4 8 K

0 .0 E + 0 0

1 .0 E + 0 3

2 .0 E + 0 3

3 .0 E + 0 3

4 .0 E + 0 3

5 .0 E + 0 3

6 .0 E + 0 3

7 .0 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m pe ra ture (K )

Mob

ility

(cm2 /V

S) 1K A

2K A3K A5K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

5 .0 E + 0 2

1 .0 E + 0 3

1 .5 E + 0 3

2 .0 E + 0 3

2 .5 E + 0 3

3 .0 E + 0 3

3 .5 E + 0 3

4 .0 E + 0 3

4 .5 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m pe ra ture (K )

Mob

ility

(cm2 /V

S) 1K A

2K A3K A5K A

(b) T s = 3 7 3 K

0 .0 E + 0 0

2 .0 E + 0 2

4 .0 E + 0 2

6 .0 E + 0 2

8 .0 E + 0 2

1 .0 E + 0 3

1 .2 E + 0 3

3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0

T e m pe ra ture (K )

Mob

ility

(cm2 /V

S) 1K A

2K A3K A5K A

(C ) T s = 4 4 8 K

Figure 7.29 Temperature variation of Mobility for ZnSe thin films of various

thicknesses deposited at different substrate temperatures.

244

7.3.2.3 TRANSPORT PROPERTIES OF ZnTe THIN FILMS

7.3.2.3.1 THICKNESS DEPENDENT TRANSPORT PROPERTIES

Hall parameters have been measured at different temperatures, as explained earlier, for ZnTe

thin films of various thicknesses deposited at different substrate temperatures. Resistivity

(zero field and 3kG), Hall-coefficient, carrier density and Hall mobility variations of ZnTe

thin films with temperature are shown in figure 7.30 to figure 7.34 respectively. Following

observations can be made easily from these figures.

1. Resistivity of all ZnTe thin films have been found to be decreasing in the range 3-

9.44x102Ω.cm as thickness of the films increases as shown in figure 7.30-7.31.

2. The sign of the Hall coefficient remains positive for all the samples of ZnTe thin

films and its magnitude remains in the range of 3-9.44x102 cm3C-1(Fig.7.32). This

indicates that all the prepared films possess holes as a majority charge carrier and

thus all the films exhibit p-type semiconducting nature. Also the majority carrier

type reversal is not observed in the studied range of temperature i.e.303-393K. It is

further found that the magnitude of Hall coefficient decreases monotonically with

the increase in film thickness as well as the substrate temperature.

3 Majority charge carrier density i.e. hole density in case of all the deposited thin

films of ZnTe increases with the thickness of the films from 2.52x1016 to 4.66x1018

cm-3 as shown in the figure 7.33.

4 Charge carrier mobility for all the deposited thin films of ZnTe decreases from

5.90x102 to 4.66 (cm2 /V.Sec) with increasing film thickness (Fig.7.34).

245

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

0 1 2 3 4 5 6 7F ilm T h ic k n e ss (k Å )

Re

sis

tiv

ity

(

cm

)3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e ss (k Å )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

1 .6 E + 0 2

1 .8 E + 0 2

2 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e ss (k Å )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 9 3 K

(c ) T s = 4 4 8 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

0 1 2 3 4 5 6 7F ilm T h ic k n e ss (k Å )

Re

sis

tiv

ity

(

cm

)3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e ss (k Å )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

1 .6 E + 0 2

1 .8 E + 0 2

2 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e ss (k Å )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 9 3 K

(c ) T s = 4 4 8 K

Figure 7.30 Variation of resistivity (Zero Field) of ZnTe thin films with film

thickness measured at different temperatures.

246

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Re

sis

tiv

ity

( 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

4 .0 E + 0 2

4 .5 E + 0 2

0 1 2 3 4 5 6 7F ilm Thic kne ss (kÅ )

Re

sis

tiv

ity

(

cm

) 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

0 1 2 3 4 5 6 7F ilm Thic kne ss (kÅ )

Re

sis

tiv

ity

(

cm

) 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c )T s = 4 4 8 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Re

sis

tiv

ity

( 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

4 .0 E + 0 2

4 .5 E + 0 2

0 1 2 3 4 5 6 7F ilm Thic kne ss (kÅ )

Re

sis

tiv

ity

(

cm

) 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

0 1 2 3 4 5 6 7F ilm Thic kne ss (kÅ )

Re

sis

tiv

ity

(

cm

) 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c )T s = 4 4 8 K

Figure 7.31 Variation of resistivity (3kG) of ZnTe thin films with film thickness

measured at different temperatures.

247

( a ) T s = 3 0 3 K

0 .0 0 E + 0 0

1 .0 0 E + 0 2

2 .0 0 E + 0 2

3 .0 0 E + 0 2

4 .0 0 E + 0 2

5 .0 0 E + 0 2

6 .0 0 E + 0 2

7 .0 0 E + 0 2

8 .0 0 E + 0 2

9 .0 0 E + 0 2

1 .0 0 E + 0 3

0 1 2 3 4 5 6 7F ilm T H ic k n e s s ( k Å )

Ha

ll C

oe

ffic

ien

t c

m3 /C

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) Ts = 373K

0 .0 E +0 0

5 .0 E +0 1

1 .0 E +0 2

1 .5 E +0 2

2 .0 E +0 2

2 .5 E +0 2

0 1 2 3 4 5 6 7F ilm THickness (kÅ )

Hal

l Co

effi

cien

t cm

3/C

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 33 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 448K

0 .0E +00

2 .0E +01

4 .0E +01

6 .0E +01

8 .0E +01

1 .0E +02

1 .2E +02

1 .4E +02

1 .6E +02

1 .8E +02

2 .0E +02

0 1 2 3 4 5 6 7Film THickness (kÅ)

Hal

l Co

effi

cien

t cm3 /C

)

303K313K323K333K343K353K363K373K383K393K

( a ) T s = 3 0 3 K

0 .0 0 E + 0 0

1 .0 0 E + 0 2

2 .0 0 E + 0 2

3 .0 0 E + 0 2

4 .0 0 E + 0 2

5 .0 0 E + 0 2

6 .0 0 E + 0 2

7 .0 0 E + 0 2

8 .0 0 E + 0 2

9 .0 0 E + 0 2

1 .0 0 E + 0 3

0 1 2 3 4 5 6 7F ilm T H ic k n e s s ( k Å )

Ha

ll C

oe

ffic

ien

t c

m3 /C

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) Ts = 373K

0 .0 E +0 0

5 .0 E +0 1

1 .0 E +0 2

1 .5 E +0 2

2 .0 E +0 2

2 .5 E +0 2

0 1 2 3 4 5 6 7F ilm THickness (kÅ )

Hal

l Co

effi

cien

t cm

3/C

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 33 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 448K

0 .0E +00

2 .0E +01

4 .0E +01

6 .0E +01

8 .0E +01

1 .0E +02

1 .2E +02

1 .4E +02

1 .6E +02

1 .8E +02

2 .0E +02

0 1 2 3 4 5 6 7Film THickness (kÅ)

Hal

l Co

effi

cien

t cm3 /C

)

303K313K323K333K343K353K363K373K383K393K

Figure 7.32 Variation of Hall Coefficient of ZnTe thin films with film thicknesses

measured at different temperature.

248

0 .0 E + 0 05 .0 E + 1 71 .0 E + 1 81 .5 E + 1 82 .0 E + 1 82 .5 E + 1 83 .0 E + 1 83 .5 E + 1 84 .0 E + 1 84 .5 E + 1 85 .0 E + 1 8

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 303 K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm-3)

0.0E+ 00

1.0E+ 18

2.0E+ 18

3.0E+ 18

4.0E+ 18

5.0E+ 18

6.0E+ 18

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b ) T s = 373K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm-3)

0.0E+005.0E+171.0E+181.5E+182.0E+182.5E+183.0E+183.5E+184.0E+184.5E+185.0E+18

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(c ) T s = 448K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm

-3)

0 .0 E + 0 05 .0 E + 1 71 .0 E + 1 81 .5 E + 1 82 .0 E + 1 82 .5 E + 1 83 .0 E + 1 83 .5 E + 1 84 .0 E + 1 84 .5 E + 1 85 .0 E + 1 8

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 303 K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm-3)

0 .0 E + 0 05 .0 E + 1 71 .0 E + 1 81 .5 E + 1 82 .0 E + 1 82 .5 E + 1 83 .0 E + 1 83 .5 E + 1 84 .0 E + 1 84 .5 E + 1 85 .0 E + 1 8

0 1 2 3 4 5 6 7

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 303 K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm-3)

0.0E+ 00

1.0E+ 18

2.0E+ 18

3.0E+ 18

4.0E+ 18

5.0E+ 18

6.0E+ 18

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b ) T s = 373K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm-3)

0.0E+ 00

1.0E+ 18

2.0E+ 18

3.0E+ 18

4.0E+ 18

5.0E+ 18

6.0E+ 18

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(b ) T s = 373K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm-3)

0.0E+005.0E+171.0E+181.5E+182.0E+182.5E+183.0E+183.5E+184.0E+184.5E+185.0E+18

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(c ) T s = 448K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm

-3)

0.0E+005.0E+171.0E+181.5E+182.0E+182.5E+183.0E+183.5E+184.0E+184.5E+185.0E+18

0 1 2 3 4 5 6 7

303K313K323K333K343K353K363K373K383K393K

(c ) T s = 448K

F ilm T h ickn ess (k Å)

Car

rier

Den

sity

(cm

-3)

Figure 7.33 Variation of carrier density of ZnTe thin films with film thicknesses

measured at different temperature.

249

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Mo

bil

ity

[c

m2 /{

VS

)]3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Mo

bil

ity

[c

m2 /{

VS

)]

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 4 4 8 K

0 .0E + 00

5 .0E + 01

1 .0E + 02

1 .5E + 02

2 .0E + 02

2 .5E + 02

3 .0E + 02

3 .5E + 02

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Mo

bil

ity

[c

m2 /{

VS

)]

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Mo

bil

ity

[c

m2 /{

VS

)]3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T s = 3 7 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Mo

bil

ity

[c

m2 /{

VS

)]

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c ) T s = 4 4 8 K

0 .0E + 00

5 .0E + 01

1 .0E + 02

1 .5E + 02

2 .0E + 02

2 .5E + 02

3 .0E + 02

3 .5E + 02

0 1 2 3 4 5 6 7F ilm T h ic k n e s s (k Å )

Mo

bil

ity

[c

m2 /{

VS

)]

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Figure 7.34 Variation of Hall mobility for ZnTe thin films with film thicknesses

measured at different temperature.

250

7.3.2.3.2 SUBSTRATE TEMPERATURE DEPENDENT TRANSPORTPROPERTIES

Variation of various Hall effect parameters like resistivity, Hall coefficient, carrier

density and mobility of ZnTe thin films with the film thickness has been studied. Figures

7.35 to 7.39 show the variation of zero field resistivity, resistivity at 3kG, Hall coefficient,

carrier density and mobility with substrate temperature for ZnSe thin films of different

thickness when measured over the temperature range 303-393 K. Following observations can

be easily made from these figures

1. As observed in the case of ZnSe thin films, resistivity of all ZnTe thin film samples

decreases with increasing substrate temperature as shown in the figures 7.35 and 7.36.

2. The values of Hall coefficient and carrier mobility decreases with the increase in

substrate temperature as shown in figure7.37 and 7.39.

3. Majority charge carrier density i.e. hole density in case of all the deposited thin films

of ZnTe increases with the substrate temperature of the films up to 1.4x1017cm-3 as

shown in the figure 7.38.

251

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

7 . 0 E + 0 2

8 . 0 E + 0 2

9 . 0 E + 0 2

1 . 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

si s

t iv

i ty

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

si s

t iv

i ty

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

7 . 0 E + 0 2

8 . 0 E + 0 2

9 . 0 E + 0 2

1 . 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

si s

t iv

i ty

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

si s

t iv

i ty

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

Figure 7.35 Variation of resistivity (Zero Field) for ZnTe thin films of different

thickness with substrate temperature measured in the temperature range

303-393K.

252

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

7 . 0 E + 0 2

8 . 0 E + 0 2

9 . 0 E + 0 2

1 . 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

4 . 5 E + 0 2

5 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

si s

t iv

i ty

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

1 . 0 E + 0 1

2 . 0 E + 0 1

3 . 0 E + 0 1

4 . 0 E + 0 1

5 . 0 E + 0 1

6 . 0 E + 0 1

7 . 0 E + 0 1

8 . 0 E + 0 1

9 . 0 E + 0 1

1 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

7 . 0 E + 0 2

8 . 0 E + 0 2

9 . 0 E + 0 2

1 . 0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

4 . 5 E + 0 2

5 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

si s

t iv

i ty

(

cm

)

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

1 . 0 E + 0 1

2 . 0 E + 0 1

3 . 0 E + 0 1

4 . 0 E + 0 1

5 . 0 E + 0 1

6 . 0 E + 0 1

7 . 0 E + 0 1

8 . 0 E + 0 1

9 . 0 E + 0 1

1 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Re

sis

tiv

ity

(

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

Figure 7.36 Variation of resistivity (3kG) for ZnTe thin films of different thickness

with substrate temperature measured in the temperature range

303-393K.

253

0 . 0 0 E + 0 01 . 0 0 E + 0 22 . 0 0 E + 0 23 . 0 0 E + 0 24 . 0 0 E + 0 25 . 0 0 E + 0 26 . 0 0 E + 0 27 . 0 0 E + 0 28 . 0 0 E + 0 29 . 0 0 E + 0 21 . 0 0 E + 0 3

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a) T = 1kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t

(cm

3 /C)

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T = 2K Å

Substrate Tem perature (K )

Hal

l Co

effi

cien

t

(cm

3 /C)

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c) T = 3kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t(c

m3 /C

)

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(d ) T = 5kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t(c

m3 /C

)

0 . 0 0 E + 0 01 . 0 0 E + 0 22 . 0 0 E + 0 23 . 0 0 E + 0 24 . 0 0 E + 0 25 . 0 0 E + 0 26 . 0 0 E + 0 27 . 0 0 E + 0 28 . 0 0 E + 0 29 . 0 0 E + 0 21 . 0 0 E + 0 3

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a) T = 1kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t

(cm

3 /C)

0 . 0 0 E + 0 01 . 0 0 E + 0 22 . 0 0 E + 0 23 . 0 0 E + 0 24 . 0 0 E + 0 25 . 0 0 E + 0 26 . 0 0 E + 0 27 . 0 0 E + 0 28 . 0 0 E + 0 29 . 0 0 E + 0 21 . 0 0 E + 0 3

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(a) T = 1kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t

(cm

3 /C)

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T = 2K Å

Substrate Tem perature (K )

Hal

l Co

effi

cien

t

(cm

3 /C)

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(b ) T = 2K Å

Substrate Tem perature (K )

Hal

l Co

effi

cien

t

(cm

3 /C)

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c) T = 3kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t(c

m3 /C

)

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 . 5 E + 0 2

4 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(c) T = 3kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t(c

m3 /C

)

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(d ) T = 5kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t(c

m3 /C

)

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

(d ) T = 5kÅ

Substrate Tem perature (K )

Hal

l Co

effi

cien

t(c

m3 /C

)

Figure 7.37 Variation of Hall coefficient for ZnTe thin films of different thickness

with substrate temperature measured in the temperature range 303-

393K.

254

( a ) T = 1 k Å

0 . 0 E + 0 0

2 . 0 E + 1 7

4 . 0 E + 1 7

6 . 0 E + 1 7

8 . 0 E + 1 7

1 . 0 E + 1 8

1 . 2 E + 1 8

1 . 4 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 E + 0 0

5 . 0 E + 1 7

1 . 0 E + 1 8

1 . 5 E + 1 8

2 . 0 E + 1 8

2 . 5 E + 1 8

3 . 0 E + 1 8

3 . 5 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

5 . 0 E + 1 7

1 . 0 E + 1 8

1 . 5 E + 1 8

2 . 0 E + 1 8

2 . 5 E + 1 8

3 . 0 E + 1 8

3 . 5 E + 1 8

4 . 0 E + 1 8

4 . 5 E + 1 8

5 . 0 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

0 . 0 E + 0 0

1 . 0 E + 1 8

2 . 0 E + 1 8

3 . 0 E + 1 8

4 . 0 E + 1 8

5 . 0 E + 1 8

6 . 0 E + 1 8

7 . 0 E + 1 8

8 . 0 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

2 . 0 E + 1 7

4 . 0 E + 1 7

6 . 0 E + 1 7

8 . 0 E + 1 7

1 . 0 E + 1 8

1 . 2 E + 1 8

1 . 4 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 E + 0 0

5 . 0 E + 1 7

1 . 0 E + 1 8

1 . 5 E + 1 8

2 . 0 E + 1 8

2 . 5 E + 1 8

3 . 0 E + 1 8

3 . 5 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

5 . 0 E + 1 7

1 . 0 E + 1 8

1 . 5 E + 1 8

2 . 0 E + 1 8

2 . 5 E + 1 8

3 . 0 E + 1 8

3 . 5 E + 1 8

4 . 0 E + 1 8

4 . 5 E + 1 8

5 . 0 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

0 . 0 E + 0 0

1 . 0 E + 1 8

2 . 0 E + 1 8

3 . 0 E + 1 8

4 . 0 E + 1 8

5 . 0 E + 1 8

6 . 0 E + 1 8

7 . 0 E + 1 8

8 . 0 E + 1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Ca

rrie

r D

en

sit

y (

cm

- 3)

3 0 3 K3 1 3 K3 2 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Figure 7.38 Variation of carrier density for ZnTe thin films of different thickness

with substrate temperature measured in the temperature range 303-

393K.

255

( d ) T = 5 k Å

0 . 0 0 E + 0 0

1 . 0 0 E + 0 1

2 . 0 0 E + 0 1

3 . 0 0 E + 0 1

4 . 0 0 E + 0 1

5 . 0 0 E + 0 1

6 . 0 0 E + 0 1

7 . 0 0 E + 0 1

8 . 0 0 E + 0 1

9 . 0 0 E + 0 1

1 . 0 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bil

ity

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

7 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bil

ity

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 0 E + 0 0

5 . 0 0 E + 0 1

1 . 0 0 E + 0 2

1 . 5 0 E + 0 2

2 . 0 0 E + 0 2

2 . 5 0 E + 0 2

3 . 0 0 E + 0 2

3 . 5 0 E + 0 2

4 . 0 0 E + 0 2

4 . 5 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bi l

i ty

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bil

ity

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( d ) T = 5 k Å

0 . 0 0 E + 0 0

1 . 0 0 E + 0 1

2 . 0 0 E + 0 1

3 . 0 0 E + 0 1

4 . 0 0 E + 0 1

5 . 0 0 E + 0 1

6 . 0 0 E + 0 1

7 . 0 0 E + 0 1

8 . 0 0 E + 0 1

9 . 0 0 E + 0 1

1 . 0 0 E + 0 2

3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bil

ity

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( a ) T = 1 k Å

0 . 0 E + 0 0

1 . 0 E + 0 2

2 . 0 E + 0 2

3 . 0 E + 0 2

4 . 0 E + 0 2

5 . 0 E + 0 2

6 . 0 E + 0 2

7 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bil

ity

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( b ) T = 2 k Å

0 . 0 0 E + 0 0

5 . 0 0 E + 0 1

1 . 0 0 E + 0 2

1 . 5 0 E + 0 2

2 . 0 0 E + 0 2

2 . 5 0 E + 0 2

3 . 0 0 E + 0 2

3 . 5 0 E + 0 2

4 . 0 0 E + 0 2

4 . 5 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bi l

i ty

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

( c ) T = 3 k Å

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 . 0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0 4 8 0 5 0 0S u b s t r a t e T e m p e r a t u r e ( K )

Mo

bil

ity

[c

m2 / (

VS

) ] 3 0 3 K3 1 3 K3 2 3 K3 3 3 K3 4 3 K3 5 3 K3 6 3 K3 7 3 K3 8 3 K3 9 3 K

Figure 7.39 Variation of mobility for ZnTe thin films of different thickness with

substrate temperature measured in the temperature range 303-393K.

256

7.3.2.3.3 TEMPERATURE DEPENDENT TRANSPORT PROPERTIES

The Hall measurement experiment was performed at various temperatures in the

range 303K to 393K at the interval of 10K. Figure 7.40 to figure 7.44 shows the variation of

different Hall parameters with temperature for ZnTe thin films of various thicknesses

deposited at various substrate temperatures. Significant variations in different Hall

parameters were observed with temperature.

It can be seen from figure 7.40 and 7.41 that as the temperature increases, films become

more conductive and resistivity decreases due to increase in grain size and reduction in

defects as discussed above. Similarly, Hall coefficient (fig.7.42) and mobility (fig.7.44)

decreases with temperature carrier density increases with temperature (fig. 7.43).

257

(b ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1 K A2 K A3 K A5 K A

(c ) T s = 4 4 8 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

1 .6 E + 0 2

1 .8 E + 0 2

2 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

( a ) T s = 3 7 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e r a tu r e (K )

Re

sis

t iv

ity

c

m)

1 K A2 K A3 K A5 K A

(b ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1 K A2 K A3 K A5 K A

(c ) T s = 4 4 8 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

1 .6 E + 0 2

1 .8 E + 0 2

2 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

( a ) T s = 3 7 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e r a tu r e (K )

Re

sis

t iv

ity

c

m)

1 K A2 K A3 K A5 K A

Figure 7.40 Variation of resistivity (Zero Field) with temperature for ZnTe thin films

of different thicknesses.

258

(a ) T s = 3 0 3 K

0 .0 E +0 0

1 .0 E +0 2

2 .0 E +0 2

3 .0 E +0 2

4 .0 E +0 2

5 .0 E +0 2

6 .0 E +0 2

7 .0 E +0 2

8 .0 E +0 2

9 .0 E +0 2

1 .0 E +0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

(b ) T s = 3 7 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

4 .0 E + 0 2

4 .5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

(c ) T s = 4 4 8 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

(a ) T s = 3 0 3 K

0 .0 E +0 0

1 .0 E +0 2

2 .0 E +0 2

3 .0 E +0 2

4 .0 E +0 2

5 .0 E +0 2

6 .0 E +0 2

7 .0 E +0 2

8 .0 E +0 2

9 .0 E +0 2

1 .0 E +0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

(b ) T s = 3 7 3 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

4 .0 E + 0 2

4 .5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

(c ) T s = 4 4 8 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e r a tu r e (K )

Re

sis

tiv

ity

cm

)

1K A2K A3K A5K A

Figure 7.41 Variation of resistivity (3kG) with temperature for ZnTe thin films of

different thicknesses.

259

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0

T e m p e ra tu re (K )

Ha

ll C

oe

ffic

ien

t (c

m3 /C

)

1K A2K A3K A5K A

( b ) T s = 3 7 3 K

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0

T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 /C

)

1 K A2 K A3 K A5 K A

(c ) T s = 4 4 8 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

1 .6 E + 0 2

1 .8 E + 0 2

2 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0

T e m p e ra tu re (K )

Ha

ll C

oe

ffic

ien

t (c

m3 C

)

1K A2K A3K A5K A

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

8 .0 E + 0 2

9 .0 E + 0 2

1 .0 E + 0 3

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0

T e m p e ra tu re (K )

Ha

ll C

oe

ffic

ien

t (c

m3 /C

)

1K A2K A3K A5K A

( b ) T s = 3 7 3 K

0 . 0 E + 0 0

5 . 0 E + 0 1

1 . 0 E + 0 2

1 . 5 E + 0 2

2 . 0 E + 0 2

2 . 5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0

T e m p e r a t u r e ( K )

Ha

ll C

oe

ffic

ien

t ( c

m3 /C

)

1 K A2 K A3 K A5 K A

(c ) T s = 4 4 8 K

0 .0 E + 0 0

2 .0 E + 0 1

4 .0 E + 0 1

6 .0 E + 0 1

8 .0 E + 0 1

1 .0 E + 0 2

1 .2 E + 0 2

1 .4 E + 0 2

1 .6 E + 0 2

1 .8 E + 0 2

2 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0

T e m p e ra tu re (K )

Ha

ll C

oe

ffic

ien

t (c

m3 C

)

1K A2K A3K A5K A

Figure 7.42 Variation of Hall coefficient with temperature for ZnTe thin films of

different thicknesses.

260

Ts = 303K

0 .0 E +0 0

5 .0 E +1 7

1 .0 E +1 8

1 .5 E +1 8

2 .0 E +1 8

2 .5 E +1 8

3 .0 E +1 8

3 .5 E +1 8

4 .0 E +1 8

4 .5 E +1 8

5 .0 E +1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e ra tu re (K )

Ca

rrie

r D

en

sit

y (

cm

-3)

1 k Å2 k Å3 k Å5 k Å

Ts = 373K

0 .0 E +0 0

1 .0 E +1 8

2 .0 E +1 8

3 .0 E +1 8

4 .0 E +1 8

5 .0 E +1 8

6 .0 E +1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e ra tu re (K )

Ca

rrie

r D

en

sit

y (

cm

-3)

1 k Å2 k Å3 k Å5 k Å

Ts = 448K

0 .0 E +0 0

5 .0 E +1 7

1 .0 E +1 8

1 .5 E +1 8

2 .0 E +1 8

2 .5 E +1 8

3 .0 E +1 8

3 .5 E +1 8

4 .0 E +1 8

4 .5 E +1 8

5 .0 E +1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e ra tu re (K )

Ca

rrie

r D

en

sit

y (

cm

-3)

1 k Å2 k Å3 k Å5 k Å

Ts = 303K

0 .0 E +0 0

5 .0 E +1 7

1 .0 E +1 8

1 .5 E +1 8

2 .0 E +1 8

2 .5 E +1 8

3 .0 E +1 8

3 .5 E +1 8

4 .0 E +1 8

4 .5 E +1 8

5 .0 E +1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e ra tu re (K )

Ca

rrie

r D

en

sit

y (

cm

-3)

1 k Å2 k Å3 k Å5 k Å

Ts = 373K

0 .0 E +0 0

1 .0 E +1 8

2 .0 E +1 8

3 .0 E +1 8

4 .0 E +1 8

5 .0 E +1 8

6 .0 E +1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e ra tu re (K )

Ca

rrie

r D

en

sit

y (

cm

-3)

1 k Å2 k Å3 k Å5 k Å

Ts = 448K

0 .0 E +0 0

5 .0 E +1 7

1 .0 E +1 8

1 .5 E +1 8

2 .0 E +1 8

2 .5 E +1 8

3 .0 E +1 8

3 .5 E +1 8

4 .0 E +1 8

4 .5 E +1 8

5 .0 E +1 8

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e ra tu re (K )

Ca

rrie

r D

en

sit

y (

cm

-3)

1 k Å2 k Å3 k Å5 k Å

Figure 7.43 Variation of carrier density with temperature for ZnTe thin films of

different thicknesses.

261

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e r a tu r e (K )

Mo

nili

ty [

cm

2 /(V

S)]

1 k Å2 k Å3 k Å5 k Å

(b ) T s = 3 7 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Mo

nil

ity

[c

m2 /(

VS

)]

1 k Å2 k Å3 k Å5 k Å

(c ) T s = 4 4 8 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Mo

nili

ty [

cm2 /(

VS

)]

1 k Å2 k Å3 k Å5 k Å

(a ) T s = 3 0 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

7 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0T e m p e r a tu r e (K )

Mo

nili

ty [

cm

2 /(V

S)]

1 k Å2 k Å3 k Å5 k Å

(b ) T s = 3 7 3 K

0 .0 E + 0 0

1 .0 E + 0 2

2 .0 E + 0 2

3 .0 E + 0 2

4 .0 E + 0 2

5 .0 E + 0 2

6 .0 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Mo

nil

ity

[c

m2 /(

VS

)]

1 k Å2 k Å3 k Å5 k Å

(c ) T s = 4 4 8 K

0 .0 E + 0 0

5 .0 E + 0 1

1 .0 E + 0 2

1 .5 E + 0 2

2 .0 E + 0 2

2 .5 E + 0 2

3 .0 E + 0 2

3 .5 E + 0 2

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 T e m p e r a tu r e (K )

Mo

nili

ty [

cm2 /(

VS

)]

1 k Å2 k Å3 k Å5 k Å

Figure 7.44 Variation of Mobility with temperature for ZnTe thin films of different

thicknesses.

262

7.4 CONCLUSIONS

In present investigation ZnX (X=Se and Te) crystals grown by Direct Vapor

Transport (DVT) technique have been used. The grown crystals were sufficient in size to

prepare samples out of them for transport properties study using variable temperature Hall

effect measurements. Few good crystals with flat signing surfaces have been selected using

optical microscope. As the grown crystals have irregular shape with almost uniform

thickness, van der Pauw geometry for Hall effect measurement has been selected for further

measurements. Silver contacts occupying minimum surface area were prepared carefully to

eliminate contact placement error. For all the crystals of ZnX, these Ohmic contacts have

been found giving linear current-voltage relationship and from these the force current values

for Hall measurement were decided. To eliminate further various measurement errors, the

Hall measurements were carried out by current and magnetic field reversals and averaged

values of various Hall parameters have been determined. Similar steps have been followed

for the square shaped thin film samples of ZnSe and ZnTe deposited by thermal evaporation

technique. Table 7.3, 7.4 and 7.5 reports the summary of all measured Hall parameters of

ZnSe and ZnTe crystals, ZnSe thin films and ZnTe thin films respectively, along with few

data collected from the published literature.

From the literature it is found that DVT technique is very rarely used technique to

grow II-VI compound semiconductor crystals because it yields in to growth of relatively

smaller crystals than other techniques like Bridgemen technique etc. Therefore, transport

property data of such crystals have not been found and here we have compared such data

obtained from the measurements made on crystals grown by other techniques. All the grown

crystals of ZnSe and ZnTe possess holes as majority carriers as the sign of Hall coefficient

remains positive throughout the temperature range of measurement. The resistivity, Hall

mobility and Hall coefficient have been found decreasing where as carrier concentration has

been found decreasing with increasing temperature in the range 303-393K. This variation is

in good agreement with the reported data in the literature as shown in the table 7.3.

263

Present work, ZnTecrystals, DVT tech.

900-2001016-1019100-101101-1026

ZnTe crystals[50]800 to 405

ZnTe grown fromvertical Bridgemannmethod, increasingtemperature decreasesmobility and increasescarrier concentration[22].

46 to 5371013 to 1016101 to 1034

ZnTe, grown by verticalBridgmann method,Increase in temperatureincreases carrierconcentration [47].

60-18001010 to 10163

ZnTe melt growth withexcess Te [54].

1012

ZnTe, Vapor Phasegrowth, Resistivitydecreases withtemperature [25].

1041ZnTeCrystal

Present work, ZnSecrystals PVT technique

300-301015- 1016101 – 102101 - 1035

ZnSe crystals, decreasewith temperature from 0to 350 (K) [50]

250 - 404

ZnSe, PVT technique.[53]

510-3403

ZnSe, melt growth withexcess Zn of 3 to 9.3mol% [52]

220-38010-12

ZnSe, ZnSe:Se withannealing in zinc melt.[51]

251010 - 1011101 to 1061ZnSeCrystal

ReferencesMobility[cm2/(VS)]

Carrierconcentration

(cm-3)

HallCoefficient(Cm3C-1)

Resistivity(.cm)

Sample

Present work, ZnTecrystals, DVT tech.

900-2001016-1019100-101101-1026

ZnTe crystals[50]800 to 405

ZnTe grown fromvertical Bridgemannmethod, increasingtemperature decreasesmobility and increasescarrier concentration[22].

46 to 5371013 to 1016101 to 1034

ZnTe, grown by verticalBridgmann method,Increase in temperatureincreases carrierconcentration [47].

60-18001010 to 10163

ZnTe melt growth withexcess Te [54].

1012

ZnTe, Vapor Phasegrowth, Resistivitydecreases withtemperature [25].

1041ZnTeCrystal

Present work, ZnSecrystals PVT technique

300-301015- 1016101 – 102101 - 1035

ZnSe crystals, decreasewith temperature from 0to 350 (K) [50]

250 - 404

ZnSe, PVT technique.[53]

510-3403

ZnSe, melt growth withexcess Zn of 3 to 9.3mol% [52]

220-38010-12

ZnSe, ZnSe:Se withannealing in zinc melt.[51]

251010 - 1011101 to 1061ZnSeCrystal

ReferencesMobility[cm2/(VS)]

Carrierconcentration

(cm-3)

HallCoefficient(Cm3C-1)

Resistivity(.cm)

Sample

Table 7.3 Reported and measured Hall parameters of ZnSe and ZnTe crystals.

264

Present work, ZnSe filmsof various thickness,deposited at differentsubstrate temperatures,

6480-511015 - 1016101-104101-1026

ZnSe films, MBE technique,3000Å, GaAs substrates,diff. substrate temperatures[44].

400-7001015 to1016106-1015

ZnSe, Thermally evaporatedfilms, Al contacts, 220 to240Å, different substratetemperatures. Highresistivity due to excessSelenium [39].

106 - 1054

ZnSe films, Spray depositiontechnique, 900 to 1400Å,Resistivity decreases andmobility increases withtemperature [48].

0.31053

ZnSe:N films, MBE, 2000Åthickness [49].

39.3 - 59610162

ZnSe films, CVD, thickness3000Å. Mobility increaseswith temperature [54].

21010161ZnSeThinFilms

ReferencesMobility[cm2/(VS)]

Carrierconcentration

(cm-3)

HallCoefficient(cm3.C-1)

Resistivity(.cm)

Sample

Present work, ZnSe filmsof various thickness,deposited at differentsubstrate temperatures,

6480-511015 - 1016101-104101-1026

ZnSe films, MBE technique,3000Å, GaAs substrates,diff. substrate temperatures[44].

400-7001015 to1016106-1015

ZnSe, Thermally evaporatedfilms, Al contacts, 220 to240Å, different substratetemperatures. Highresistivity due to excessSelenium [39].

106 - 1054

ZnSe films, Spray depositiontechnique, 900 to 1400Å,Resistivity decreases andmobility increases withtemperature [48].

0.31053

ZnSe:N films, MBE, 2000Åthickness [49].

39.3 - 59610162

ZnSe films, CVD, thickness3000Å. Mobility increaseswith temperature [54].

21010161ZnSeThinFilms

ReferencesMobility[cm2/(VS)]

Carrierconcentration

(cm-3)

HallCoefficient(cm3.C-1)

Resistivity(.cm)

Sample

Table 7.4 Reported and measured Hall parameters of ZnSe thin films

265

Present work, ZnTefilms of variousthicknesses, depositedat different substratetemperatures.

590-331016-1018100-102100 -1025

ZnTe films, Thermalevaporation tech.Glass/silicon substrate,220 to 1700Å thickness[57].

10194

ZnTe thin films,Electrodeposition (0.65V),3000Å, Au coated Cusubstrate [56].

104 -1053

ZnTe films, Brush platingtechnique at -0.9Vpotential on conductingglass and titaniumsubstrates at difffferenttemperatures [46].

5 – 601014 to 10152

ZnTe:N films, MBE,2000Å [49]

40-1000410161ZnTeThinFilms

ReferencesMobility[cm2/(VS)]

Carrierconcentration

(cm-3)

HallCoefficient(cm3.C-1)

Resistivity(.cm)

Sample

Present work, ZnTefilms of variousthicknesses, depositedat different substratetemperatures.

590-331016-1018100-102100 -1025

ZnTe films, Thermalevaporation tech.Glass/silicon substrate,220 to 1700Å thickness[57].

10194

ZnTe thin films,Electrodeposition (0.65V),3000Å, Au coated Cusubstrate [56].

104 -1053

ZnTe films, Brush platingtechnique at -0.9Vpotential on conductingglass and titaniumsubstrates at difffferenttemperatures [46].

5 – 601014 to 10152

ZnTe:N films, MBE,2000Å [49]

40-1000410161ZnTeThinFilms

ReferencesMobility[cm2/(VS)]

Carrierconcentration

(cm-3)

HallCoefficient(cm3.C-1)

Resistivity(.cm)

Sample

Table 7.5 Reported and measured Hall parameters of ZnTe thin films

266

Apart from the thermal evaporation technique, there have been verities of techniques

adopted to deposit thin films of ZnSe and ZnTe and few such data of transport properties

measurements on these thin films are also compared with the results of present investigation.

It is found that the measured data of transport properties in case of ZnSe and ZnTe

crystals and thin films are in good agreement with the reported data as shown in table 7.4 and

7.5. They also show the similar trend of decreasing resitivity, carrier concentration and

mobility along with increasing Hall coefficient in the temperature range of measurement i.e.

303-393K. The temperature variation of mobility, in a limited range of temperature, is in

good agreement with such measurements made in the similar range and it is found that at

higher temperature optical phonon scattering is dominant.

For thin films of ZnSe and ZnTe, the thickness and substrate temperature variation of

Hall parameters have been investigated in the temperature range 303-393K. It is found that

with increasing thickness and substrate temperature the sign of Hall coefficient remains

positive indicating that the majority carriers are holes and there is no conductivity type

reversal in the measured range of temperatures. All Hall parameters have been found

improving as thickness of the films and substrate temperature are increasing because of the

fact that thicker films are continuous films ending their growth with smoother surfaces as

substrate temperature is increased as evident from the AFM data given in chapter-6.

267

REFERENCES

1. M.J.Deen, Electrical and Computer Engineering, CRL 226, McMaster University,

Hamilton, Ontario,Canada L8S 4K1

2. Venkatchalam SMangalaraja D, Narayandass Sa.K, Physica B, Physics of Condensed

Matter, Vol.393, Issue 1-2 (2006) 47-55

3. S.Chaliha, M.N. Borah, P.C.Sharma and A.Rahman, Proceedings of DAE Solid State

Physics Symposium, (2005)

4. S.Venkatchalam, D.Mangalaraj, Sa. K. Narayandass, K.Kim, and J.Yi, Vacuum 81

(2007) 928-933

5. A.N.Avdonin, G.V.Kolibaba, D.D.Nedeoglo, N.D.Nedeoglo and V.P.Sirkeli, Journal

of Optoelectronics and Advanced Materials Vol.7, 2 (2005) 733-737

6. S.Venkatchalam, D.Mangalraj and Sa. K.NArayandass, J.Phys D, Appl.Physics 39

(2006) 4777-4782

7. D.N.Bose and S. Bhunia, Bull.of Material Science, Vol.28, 7 (2005) 647-650

8. R.Amutha, A. Subbarayan, R. Sathyamurthy, K.Natarajan and S.Velumani, Journal of

new materials for Electrochemical systems 10 (2007) 27-31

9. R.J.Gould and C.J.Bowler, Thin Solid Films, 164 (1988) 281

10. B.B.Ismail and R.D.Gloud, Phys. Status Solidi(a), 115 (1989 )237

11. S.Gogoi and K. Bagua, Thin Solid Films, 92 (1982) 227

12. R.Sathyamurthy, Sa. K.Narayandass, C. Balasubrimanian and D.Mangalaraj, Proc. of

Solid State Phys. Symp. 33C (1991) 409

13. Taro Hino and Ken Yamashita, Japan J. App.Physics, 13(6) (1974) 1015

14. N.C.Parakh and J.C.Garg, Ind. Journal of Pure and Appl. Phys. 2591987)110

15. Marc Burgelaman, Thin Solid Films, 70 (1980) 1

16. Jaydev Pattar, Shilpa N. Sawant, M. NAgaraja, N.Shashank, K.M.Balkrishna, Ganesh

Sanjeev and H.M.Mahesh, Int. Journal of Electrochmical Sci., 4 (2009) 369-376

17. Petr Klapetek, Ivan Ohlidal, Alberto Montaigne-Ramil, Alberta Bonanni, David

Stifter, Helmut Sitter, Jp. J. App. Phys, 42 (2003) 4706

268

18. Q.Guo, M.Ikejra, M. Nishio, and H.Ogawa, Sol. Stat.Commun, 106(1996) 813

19. A.A.Ibrahim, Vacuum 81 (2006) 527

20. K.R.Murli, A.Clara Dhanemozhi and Rita John, Chalcogenide letters, Vol-5, 11

(2008) 277-280

21. M.G.M.Chaudhary, M.R.Islam, M.M.Rahman, M.O.Hakim, M.K.R.Khan, K.J.Kao

and G.R.Lai, acta physica slovaca, Vol.54, 4 (2004) 417-425

22. S.Bhunia and D.N.Bose, Journal of Crystal Growth, 186 (1998) 535-542

23. R.G.VaSleev, P.N.Krylov and E.A.Romanov, Journal of Surface investigation, X- ray

synchrotron and Neutron techniques, Vol-1, 1 (2007) 35-39

24. Mohd. Shakir, B.K.Singh, R.K.Gaur, Binay Kumar, G.Bhagavannarayana and

M.A.Wahab, Chalcogenide letters, Vol.6, 12 (2009) 655-660

25. Yu.V.Klevkov, S.A.Kolosov, V.A.Krivobok, V.P.Martovisky and S.N.Nikolaev,

Semiconductors, Vol-42, 11 (2008) 1264-1269

26. M.J.Deen, Electrical characterization techniques for semiconductor-SiO2 interface –

A Review, Eds. R.E.Sah, M.J.Deen, D. Landheer, K.B.Sundaram, W.D.Brown and D.

Misra, the 203rd Meeting of the Electrochemical Society, Paris, France, pp. 3-21 (27

April – 2 May, 2003)

27. Proceedings of the Symposium on Diagnostic Techniques for Semiconductor

Materials and Devices, Volume 97-12, (The electrochemical Society Press, New

Jersey, 1997)

82. D.Schroder, Semiconductor Material and Device Characterization, Second Edition,

(Jhon Wiley & Sons, New York, 1998)

29. W.Runyan, T.Shaffner, Semiconductor Measurements & Instrumentation, 2nd edn.

(Mc Graw Hill, New York, 1997)

30. Lakeshore 7504 user’s manual

31. L.J.Van der Pauw, Philips Technical Report, 13 (1958) 1

32. L.J.Van der Pauw, Philips Technical Review, 26 (1958) 220

33. D.W.Koon and C.J.Knickerbocker, Rev. Sci. Instrum, 69(10) (1998) 3625

34. D.W.Koon and C.J.Knickerbocker, Rev. Sci. Instrum , 63(1) (1992) 587

35. D.W.Koon and C.J.Knickerbocker, Rev. Sci. Instrum , 64(2) (1993) 510

36 D.W.Koon and C.J.Knickerbocker, Rev. Sci. Instrum, 71 (2000) 587

269

37. Lakeshore 7500/9500 series Hall system users manual

38. K/Dieter Schroder, (Ed.) (1990), Semiconductors material and device

characterization, Jhon Wiley & Sons, Inc. Publications

39. M.G. Syed Basheer Ahamed, V.S.Nagarethinam, A.R. Balu, A. Thayumanavan,

K.R.Murli, C. Sanjeevireja and M. Jaychandran Crystal Research Technology, 45,

No. 4, (2010) 421-426

40. T. Mahalingum, V.S.Jhon, S. Rajendraanand, P.J. Sebastain, Semicondictor Science

and Technology, 17 (2002) 465

41. R.Amutha, A. Subbarayan and R. Sathyamurthy, Crystal Research Technology, 41

No. 12 (2009) 1174-1179

42. F. M. Abou El-Ela, Egypt. J. Sol.Vol 23, 1 (2000)

43. Gowrish K. Rao, KAsturi V. Bangera and G. K. Shivkumar, Vacuum, V. 83, 12

(2009) 1485-1488

44. Takafumi Yao, Mutsou Ogura, Seiichi Matsuok and Toshihide Morishta, Japanees

Journal of Applied Physics, V.22, 3 (1983) L144-L146

45. K.N.Raju, R.P.Vijayalakshmi, R. Venugopal, D. R. Reddy and B.K. Reddy, Material

Letters, V. 13, 6 (1992) 336-341

46. K.R.Murali, M. Ziyauddin and N. Jayaprakash, Solid State Electronics, V. 50, 11-12

(2006) 1692-1695

47. T. L. Larsen and D. A. Stevenson, Journal of Applied Physics, V. 44, 2 (1973) 843-

847

48. M. Bedir, M. Oztas, O. F. Bakkalogu and R. Ormanci, Eur. Phys. J. B. 45 (2005) 465-

471

49. Y. Fan, J. Han, L. HE, J. Sarare and R. L. Gunshor, Journal of Electronic Materials,

V. 23, 3 (1994) 245-249

50. D. Krnzer, J. Phys. C: Solid State Phys. V. 6 (1973) 2977-2987

51. Yu. F. Vaksman, Yu. A. Nitsuk, Yu. N. Purtov and P.V. Shapkin, Semiconductors, V.

37, 2 (2003) 145-147

52. Iaso Kikuma and Mitsou Furukoshi, Japanese Journal of Applied Physics, 24 (1985)

L941 – L943

270

53. N. Sankar and K. Ramchandran and C. Sanjeeviraja, Journal of Crystal Growth, V.

235, 1-4 (2002) 195-200

54. V.P.Gribkovski, V.A.Zaporozhchenko, V.A.Ivanov, A.V.KAchinskil,

V.V.Parashchuk and G.P.Yablonski, Sov. Journal of Quantum Electronics, 9(10)

(1979) 1304-1307

55. Takafumi Yao, Mutsou Ogura, Seiichi Matsuok and Toshihide Morishta, Applied

Phys. Letters, 43 (5) (1983) 499-501

56. Takashiro Ishizaki, Takeshi Ohtomo and Akio Fuwa, J. Phys. D, Appl. Phys, 37

(2004) 255-260

57. M.A.M. Seyam, H.T. El-Shair and G. F. Salem, Eur. Phys. J. Appl. Phys. 41 (2008)

221-227

58. O.E.Emelyanenko, G.N.Ivanova, T.S.Lagunova, D.D. Nadeoglo,G.M.Shmelev and

A.V.Simashkevich, Physica Status Solidi (b), V. 96, 2(1979) 823-833