Electronic and Optical Properties of Sillicon and Titanium Nanowires
-
Upload
vishnu0751 -
Category
Documents
-
view
218 -
download
0
Transcript of Electronic and Optical Properties of Sillicon and Titanium Nanowires
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
1/43
lectronic and optical properties ofSillicon and titanium Nanowires
Ab- intio study
Project Report
By
FlorinaRegius
SRM UNIVERSITY
Under the guidance of
Dr.AnuragSrivastav
Computational Nano Science and Technology Lab CNTL
ABV- Indian Institue of Information Technology and Management , Gwalior
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
2/43
Acknowledgement
I would like to take this opportunity to express my sincere thanks
to Dr.AnuragSrivastav for his valuable guidance and support
through out my project. I have been benefitted a lot from his
erudite Academic levels and conscientious Research Institute.
I would like to extend my gratitude to Sumit Jain for his dynamic
guidance , sharing valuable experiences , discussions , opinions and
also giving valuable reviews to my project and study.
I additionaly thank Mr.Vikas for all his help . I am also grateful to
my parents . Without their support and encouragement , I would
have not able to come so far. I also acknowledge the ABV Indian
Institue of Information Technology and Management , Gwalior for
the Infrastructural support provided to the project work .
FlorinaRegius
Date:
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
3/43
Declaration
I hereby declare that the work which is being
presented in this report entitled Electronic and
optical properties of Sillicon and titanium
Nanowires : Ab initio study is an authentic
record of my own work carried out under the
guidance of Dr.AnuragSrivastava , ComputationalNano Science and technology Lab (CNTL) ,ABV-
IIITM, Gwalior.
I further declare that the matter embodied in this
report has not been submitted by me as a whole
or in part at any other Institution /University.
FlorinaRegius
(Btech 4 semnanotech)
Registration Number = 1231210022
SRM university
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
4/43
Certificate
This is to certify that Miss. FlorinaRegius , a student of Btech (Nanotech ) from
SRM UNIVERSITY , Chennai , Registration Number 1231210022 has successfully
completed her winter training /project on the topic Electronic and Optical
properties of Sillicon and titanium nanowire : Ab initio study under the
guidance of my supervision from 1/12/13 to 25/12/13 . During her stay , I
personally found her very sincere , dedicated and always keen to learn newer
things , this qualities may lead to build her career as a great researcher.
The declaration made by Miss. FlorinaRegius in her report is correct to the best
of my knowledge and the report is bonafide work done by her at the
Computational Nano Science and Technology lab (CNTL) , ABVIndian Institue
Of Information Technology and Management , Gwalior .
I wish her success in all her endeavours.
Dr.AnuragSrivastava
Computational Nanosicence and technology Lab (CNTL)
ABV- Indian Institute of Information Technology and Management
Gwalior - 474010
ATAL BIHARI VAJPAYEEIndian
Institue of Information
Technology and Management ,
Gwalior
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
5/43
Introduction
Sillicon Nanowire
Silicon nanowires can enhance broadband optical absorption and reduce radial
carrier collection distances in solar cell devices. Arrays of disordered nanowiresgrown by vapor-liquid-solid method are attractive because they can be grown
on low-cost substrates such as glass, and are large area compatible. Here, we
experimentally demonstrate that an array of disordered silicon nanowires
surrounded by a thin transparent conductive oxide has both low diffuse and
specular reflection with total values as low as < 4% over a broad wavelength
range of 400 nm < < 650nm. These anti-reflective properties together with
enhanced infrared absorption in the core-shell nanowire facilitates enhancement
in external quantum efficiency using two different active shell materials:amorphous silicon and nanocrystalline silicon. As a result, the core-shell
nanowire device exhibits a short-circuit current enhancement of 15% with an
amorphous Si shell and 26% with a nanocrystalline Si shell compared to their
corresponding planar devices.
Titanium Nanowire
The structures of free-standing titanium nanowires are studied by using a
genetic algorithm with a tight-binding potential. Helical multi-walledcylindrical structures are obtained and pentagonal packing is found for these
thin wires with diameters from 0.747 to 1.773 nm. The angular correlation
functions and vibrational properties of nanowires are discussed. We have
further calculated the electronic structures of the titanium nanowires with the
plane-wave pseudopotential method. Bulk-like continuous electronic bands are
found in the Ti wires thicker than 1 nm. The vibrational and electronic
properties of titanium nanowire are significantly dependent on the multi-walled
structure of the nanowire.
The thermal stability and melting behavior of ultrathin titanium nanowires with
multi-shell cylindrical structures are studied using molecular dynamic
simulation. The melting temperatures of titanium nanowires show remarkable
dependence on wire sizes and structures. For the nanowire thinner than 1.2 nm,
there is no clear characteristic of first-order phase transition during the melting,
implying a coexistence of solid and liquid phases due to finite size effect. An
interesting structural transformation from helical multi-shell cylindrical
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
6/43
Literature Survey
1.1: Sillicon Nanowire
It is well-known that one-dimensional nanostructures reduce pulverization of
silicon (Si)-based anode materials during Li ion cycling because they allow
lateral relaxation. However, even with improved designs, Si nanowire-based
structures still exhibit limited cycling stability for extended numbers of cycles,
with the specific capacity retention with cycling not showing significant
improvements over commercial carbon-based anode materials. We have found
that one important reason for the lack of long cycling stability can be the
presence of milli- and microscale Si islands which typically form under
nanowire arrays during their growth. Stress buildup in these Si island
underlayers with cycling results in cracking, and the loss of specific capacity forSi nanowire anodes, due to progressive loss of contact with current collectors.
We show that the formation of these parasitic Si islands for Si nanowires grown
directly on metal current collectors can be avoided by growth through anodized
aluminum oxide templates containing a high density of sub-100 nm nanopores.
Using this template approach we demonstrate significantly enhanced cycling
stability
Sinanowire-based lithium-ion battery anodes, with retentions of more than
1000 mAh/g discharge capacity over 1100 cycles.
Silicon nanowires can enhance broadband optical absorption and reduce radial
carrier collection distances in solar cell devices. Arrays of disordered nanowires
grown by vapor-liquid-solid method are attractive because they can be grown
on low-cost substrates such as glass, and are large area compatible. Here, we
experimentally demonstrate that an array of disordered silicon nanowires
surrounded by a thin transparent conductive oxide has both low diffuse andspecular reflection with total values as low as < 4% over a broad wavelength
range of 400 nm < < 650nm. These anti-reflective properties together with
enhanced infrared absorption in the core-shell nanowire facilitates enhancement
in external quantum efficiency using two different active shell materials:
amorphous silicon and nanocrystalline silicon. As a result, the core-shell
nanowire device exhibits a short-circuit current enhancement of 15% with an
amorphous Si shell and 26% with a nanocrystalline Si shell compared to their
corresponding planar devices.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
7/43
The fiftieth anniversary of silicon-wire research was recently commemorated, agood occasion to take a look back and attempt to review and discuss some ofthe essential aspects of silicon-wire growth, of the growth thermodynamics, andof the electrical properties of silicon nanowires. The statement of a fiftieth
anniversary refers to the publication of Treuting and Arnold of 1957,[1] which,to the best of our knowledge, represents the first publication on Si wire growth.Therein, the authors report on the successful synthesis of silicon whiskers withh111i orientation. At these times, the term whisker was most commonly used inreference to grown filamentary silicon crystals, often times still havingmacroscopic dimensions (see, e.g., the impressively large wires shown in[2]). Inaddition to the terms whisker or wire, nanorod is also sometimesused.[3,4]Throughout this work, the traditional name whisker will not be used,even when referring to the works of old times. Instead, we will use the termsilicon wire for filamentary crystals of diameters larger than about hundrednanometers. The term nanowire will be employed in reference to wires ofdiameters smaller than about hundred nanometers. When general aspects notrestricted to a certain size range are discussed, we will use the more generalterm wire. We will try to stick to thisconvention, albeit not with uttermost strictness. Going back to the 1960s, onlyseven years after the work of Treuting and Arnold was published[1] didresearch on silicon wires start to really gain momentum, a process clearlycatalyzed by the pioneering work of Wagner and Ellis.[5] In this paper, theyclaimed their famous vaporliquidsolid (VLS) mechanism of single-crystal
growth, which set the basis for a new research field and which until todayrepresents the mostcommon way to synthesize silicon wires. As shown inFigure 1, research on silicon wires basically started with the publication ofWagner and Ellis, flourished for about 10 years, and then ebbed away.
Nevertheless, this time was sufficientfor the discovery of many of the fundamental aspects of VLS silicon-wiregrowth.[6]The second phase in silicon-wire research started in the mid1990s,when advances in microelectronics triggered a renewedinterest in siliconnownanowireresearch. Morales and Lieber[7] managed to synthesize nanowires
of truly nanoscopicdimensions and introduced laser ablation as a new methodforand its implications for the silicon-nanowire growth velocity. Last,we will turn our attention to the electrical properties of silicon nanowires anddiscuss the different doping methods. Then, three effects essential for theconductivity of a silicon nanowire are treated. These are the diameterdependence of the dopantionization efficiency, the influence of surface traps on the charge-carrierdensity, also causing a diameter dependence, andthe charge-carrier mobility in silicon nanowires.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
8/43
1.2 Titaniun Nanowire
The structures of free-standing titanium nanowires are studied by using a
genetic algorithm with a tight-binding potential. Helical multi-walled
cylindrical structures are obtained and pentagonal packing is found for thesethin wires with diameters from 0.747 to 1.773 nm. The angular correlation
functions and vibrational properties of nanowires are discussed. We have
further calculated the electronic structures of the titanium nanowires with the
plane-wave pseudopotential method. Bulk-like continuous electronic bands are
found in the Ti wires thicker than 1 nm. The vibrational and electronic
properties of titanium nanowire are significantly dependent on the multi-walled
structure of the nanowire
One-dimensional single crystal nanostructures have garnered much attention,from their low-dimensional physics to their technological uses, due to their
unique properties and potential applications, from sensors to interconnects.
There is an increasing interest in metallic titanium nanowires, yet their single
crystal form has not been actualized. Vaporliquidsolid (VLS) and template-
assisted top-down methods are common means for nanowire synthesis;
however, each has limitations with respect to nanowire composition and
crystallinity. Here we show a simple electrochemical method to generate single
crystal titanium nanowires on monocrystallineNiTi substrates. This work is asignificant advance in addressing the challenge of growing single crystal
titanium nanowires, which had been precluded by titanium's reactivity.
Nanowires grew non-parallel to the surface and in a periodic arrangement along
specific substrate directions; this behavior is attributed to a defect-driven
mechanism. This synthesis technique ushers in new and rapid routes for single
crystal metallic nanostructures, which have considerable implications for
nanoscale electronics.A fluorescent erbium/ytterbium co-doped fluoride
nanocrystal glued at the end of a sharp atomic force microscope tungsten tipwas used as a nanoscale thermometer. The thermally induced fluorescence
quenching enabled observation of the heating and measurement of the
temperature distribution in a Joule-heated 80 nm wide and 2 m long titanium
nanowire fabricated on an oxidized silicon substrate. The measurements have
been carried out in an alternating heating mode by applying a modulated current
on the device at low frequency. The heating is found to be inhomogeneous
along the wire, and the temperature in its center increases quadratically with the
applied current. Heat appears to be confined mainly along the wire, with weak
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
9/43
lateral diffusion along the substrate and in the lateral metallic pads. The lateral
resolution of this thermal measurement technique is better than 250 nm. It could
also be used to study thermally induced defects in nanodevices.
The structures of free-standing titanium nanowires are studied by using agenetic algorithm with a tight-binding potential. Helical multi-walled
cylindrical structures are obtained and pentagonal packing is found for these
thin wires with diameters from 0.747 to 1.773 nm. The angular correlation
functions and vibrational properties of nanowires are discussed. We have
further calculated the electronic structures of the titanium nanowires with the
plane-wave pseudopotential method. Bulk-like continuous electronic bands are
found in the Ti wires thicker than 1 nm. The vibrational and electronic
properties of titanium nanowire are significantly dependent on the multi-walledstructure of the nanowire.
The thermal stability and melting behavior of ultrathin titanium nanowires with
multi-shell cylindrical structures are studied using molecular dynamic
simulation. The melting temperatures of titanium nanowires show remarkable
dependence on wire sizes and structures. For the nanowire thinner than 1.2 nm,
there is no clear characteristic of first-order phase transition during the melting,
implying a coexistence of solid and liquid phases due to finite size effect. An
interesting structural transformation from helical multi-shell cylindrical to bulk-like rectangular is observed in the melting process of a thicker hexagonal
nanowire with 1.7 nm diameter.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
10/43
Computational Method
The purpose of this tutorial is to show how to set up and perform calculations for a devicebased on a silicon nanowire. You will define the structure of a H-passivated silicon nanowirealong the (100) direction, and set up a field-effect transistor (FET) structure with a cylindricalwrap-around gate.
Note
We will primarily use the graphical user interface Virtual NanoLab (VNL) for setting upand analyzing the results. To familiarize yourself with VNL, it is recommended to gothrough theVNL Tutorial.
The underlying calculation engines for this tutorial are ATK-DFTand ATK-SE. A
complete description of all the parameters, and in many cases a longer discussion abouttheir physical relevance, can be found in theATK Reference Manual.
In order to run this tutorial, you must have a license for both ATK-SE and ATK-DFT. Ifyou do not have one, you may obtain a time-limited demo license by contactingQuantumWise viaour website.
Setting up the Si (100) nanowire geometry
Start VNL and create a new project and give it a name then click Open. Next launch the
Builder via the icon on the toolbar.
In the builder, click Add From Database.... Type silicon fcc in the search field to
locate the diamond phase of silicon. Click the icon in the lower right-hand corner of theDatabase window to add the structure to the Stash in the Builder.
Next unfold the Builders panel bar in the right-hand column of the Builder and open theSurface (Cleave)... tool.
In the surface cleave tool,
Keep the default (100) cleave direction, and press Next >.
Keep the default surface lattice, and press Next >.
Keep the default supercell, this will ensure that the wire direction is perpendicular tothe surface, and press Next >.
Press the Finish button to add the cleaved structure to the Stash.
http://quantumwise.com/documents/manuals/latest/VNLTutorial/XHTMLhttp://quantumwise.com/documents/manuals/latest/VNLTutorial/XHTMLhttp://quantumwise.com/documents/manuals/latest/VNLTutorial/XHTMLhttp://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/chap.atkse.htmlhttp://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/chap.atkse.htmlhttp://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/chap.atkse.htmlhttp://quantumwise.com/products/free-trialhttp://quantumwise.com/products/free-trialhttp://quantumwise.com/products/free-trialhttp://quantumwise.com/products/free-trialhttp://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/chap.atkse.htmlhttp://quantumwise.com/documents/manuals/latest/VNLTutorial/XHTML -
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
11/43
Next open Bulk Tools Repeatand enter A=2, B=2, C=1, and press Apply.
Press Ctrl+R to reset the view in the Builder.
To finalize the setup perform the following steps:
Open Bulk Tools Lattice Parametersand set the length of the A and Bvectors to 20 .
Open Coordinate Tools Centerand center the structure in all directions.
Click the H-passivator in the left-hand tool bar to passivate the structure.
Defining and running the calculation
In the following you will relax the geometry using DFT-GGA, and calculate the bandstructure of the nanowire with 3 different models, DFT-GGA, DFT-MetaGGA, and theExtended Hckel model.
Note
The Meta-GGA and the Extended Hckel models cannot be used for relaxation.
For this purpose:
Add a New Calculator. Add Optimization/OptimizeGeometry Add Analysis/Bandstructure. Add a New Calculator. Add Analysis/Bandstructure. Add a New Calculator. Add Analysis/Bandstructure. Set the output file to si_100_nanowire.nc
You should now have the following setting.
Open the first New Calculatorblock, and make the following settings:
Set the k-point sampling to: 1, 1, 11. Change the exchange-correlation potential to GGA.
Open the second New Calculatorblock, and make the following settings:
Set the k-point sampling to: 1, 1, 11. Change the exchange-correlation potential to MGGA.
Open the last New Calculatorblock, and make the following settings:
Select the "ATK-SE: Extended Hckel" calculator.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
12/43
Uncheck No SCF iteration to make the calculation selfconsistent.
Set the k-point sampling to: 1, 1, 11. Increase the Density mesh cut-off to 20 Hartree.
Electronic structure and optical properties of silicon
Table of Contents
Setting up the calculation Running and analyzing the calculation
o DOS of silicono Optical spectrum
Setting up the calculation
Start VNL, create a new project and give it a name, then select it and click Open. Launch the
Builder by pressing the icon on the toolbar.
In the builder, click Add From Database.... Type silicon in the search field, andselect the silicon standard phase in the list of matches. Information about the lattice, includingits symmetries (e.g. that the selected crystal is face centered cubic), can be seen in the lower
panel.
Double-click the line to add the structure to the Stash, or click the icon in the lower right-hand corner.
Now send the structure to the Script Generatorby clicking the "Send To" icon in thelower right-hand corner of the window, and select Script Generator(the defaultchoice, highlighted in bold) from the pop-up menu.
In the Script Generator,
Add a New Calculator.
Add a Analysis>Bandstructure.
Add a Analysis>DensityOfStates.
Add a Analysis>OpticalSpectrum.
Change the output filename to si.nc
The next step is to adjust the parameters of each block.
Open the New Calculator block by double-clicking it, and
select the ATK-DFT calculator (selected by default), set the k-points to (4,4,4), select the exchange-correlation functional to MGGA, and finally under "Basis set/exchange correlation", select the
DoubleZetaDoublePolarizedbasis set for Si.
http://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect1.setup.sihttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect1.setup.sihttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect1.running.sihttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect1.running.sihttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect2.si.bandhttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect2.si.bandhttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect2.si.opticalhttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect2.si.opticalhttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect2.si.opticalhttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect2.si.bandhttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect1.running.sihttp://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html#sect1.setup.si -
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
13/43
Results and discussions
Si Nanowire
Band Structure Analysis
By noticing the graphs , we can see that when sillicon is not doped by any
Aluminium atoms , then we can clearly observe the that there are no lines
which are crossing the fermilevel . The first curve is at 0.13 above the fermi
level and the lowest curve is at -0.3 below the fermi level. We can observe
the small gap which clearly shows it is semi conductor from fig. a .In fig.b ,
we can see that when sillicon is doped by two Aluminium atoms , then we
can clearly observe the that there is one line which is crossing the fermi
level . The first curve is at 0.03 above the fermi level and the lowest curve is
at -0.01 below the fermi level. We can observe the crossing of line which
clearly shows it is doped.Infig.c , we can see that when sillicon is doped by
four Aluminium atoms , then we can clearly observe the that there is two
line which is crossing the fermi level . The first curve is at 0.02 above the
fermi level and the lowest curve is at -0.06 below the fermi level. We can
observe the crossing of line which clearly shows it is doped. In fig.d, we can
see that when silliconis doped by six Aluminium atoms , then we can clearly
observe the that there is four line which is crossing the fermi level . The first
curve is at 0.01 above the fermi level and the lowest curve is at -0.07 below
the fermi level. We can observe the crossing of lines which clearly shows itis doped.
Density of States
By observing the graph , we can clearly see the pecularity in them . The
peak which is near the fermi level shows downward drift and other peaks
shows near by it shows the upward lift . By seeing the first graph which
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
14/43
represents the pure sillicon wire which doesnt have doping . The
downward drift of peak which is on the fermi level is at 8 of y axis which is
density of states. The other thing is graph is not much denser from figure
e.In the figure f , when we dope the sillicon nanowire with two Phosphrous
atoms then there is downward shift in the peak which is at middle of fermi
level and the downward drift increaes on increase of doping of atoms . The
downward shift goes 2 which is at density of states in y axis. On comparing
with the other graph , we can see that it is little more denser than other
grpah .In the figure g , when we dope the sillicon nanowire with four
Phosphorus atoms then there is downward shift in the peak which is at
middle of fermi level and the downward drift increase on increase of doping
of atoms . The downward shift goes 1.2 which is at density of states in yaxis. On comparing with the other graph , we can see that it is more denser
than other graph .In the figure h , when we dope the sillicon nanowire with
six Phosphorus atoms then there is downward shift in the peak which is at
middle of fermi level and the downward drift increase on increase of doping
of atoms . The downward shift goes 0.2 which is at density of states in y
axis. On comparing with the other graph , we can see that it is little most
denser than other graph .
Optical Spectrum
By observing the graphs , we can say that in the first graph which shows
pure sillicon without doping , the red line is at 3 , blue line at 2 and
green line at 1.7 which is for real part and all these lines coincide with
each other an the end and seems to be like one line but on the other
hand by looking at the imaginary part we can observe that initial point of
the three peaks formed by red,blue and green are at o but the peaks are
raising to 2 , 1.5 and 1 and then at end these three lines coincide each
other and merge with each other at the end in the figure I . When the
sillicon nanowire is doped with two aluminium atoms then we can see
that red line forms a peak and shows a rise but other two lines are at 1.5
and 1.3 and doesnt show a merge at end as usual in the real part . In the
case of imaginary part , the red line shows a peak whose initial point is 0and touches the 1.5 and other lines and doesnt show any merge at end.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
15/43
When the sillicon nanowire is doped with four aluminium atoms then we
can see that red line forms a peak and shows a rise at 2 and green line is
at 0.3 and the blue line became invisibleand doesnt show a merge at
end as usual in the real part . In the case of imaginary part , the red line
shows a peak whose initial point is 0 and touches the 1.2 and other lines
and doesnt show any merge at end. When the sillicon nanowire is
doped with six aluminium atoms then we can see that red line forms a
peak and shows a rise at 5 and green line is at 3 and the blue line at 1.8
doesnt show a merge at end as usual in the real part . In the case of
imaginary part , the red line shows a peak whose initial point is 0 and
touches the 4 and other lines and doesnt show any merge at end. It
shows multi peaks may be becoz of increasing metallic nature .Byobserving the above graphs , we can say that in the first graph which
shows pure sillicon without doping , the red line is at 3 , blue line at 2
and green line at 1.7 which is for real part and all these lines coincide
with each other an the end and seems to be like one line but on the
other hand by looking at the imaginary part we can observe that initial
point of the three peaks formed by red,blue and green are at o but the
peaks are raising to 2 , 1.5 and 1 and then at end these three lines
coincide each other and merge with each other at the end .By observing
the above graphs , we can say that in the first graph which shows pure
sillicon nanowire doping it with two aluminium atoms , the red line is
at 2.5 , blue line at 0.3 and green line at 0.2 which is for real part and all
these lines coincide with each other an the end and seems to be like one
line but on the other hand by looking at the imaginary part we can
observe that initial point of the three peaks formed by red,blue and
green are at o but the peaks are raising to 1.5 , 0.5 and 0.2 and then atend these three lines coincide each other and merge with each other at
the end .By observing the above graphs , we can say that in the first
graph which shows pure sillicon nanowire by doping it with four
aluminium atoms , the red line is at 10 , blue line at 4and green line at 2
which is for real part and all these lines coincide with each other an the
end and seems to be like one line but on the other hand by looking at
the imaginary part we can observe that initial point of the three peaks
formed by red,blue and green are at o but the peaks are raising to 3 , 1.5
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
16/43
and 0.2 and then at end these three lines coincide each other and merge
with each other at the end .By observing the above graphs , we can say
that in the first graph which shows pure sillicon nanowire by doping it
with six aluminium atoms , the red line is at 2.2 , blue line at 1.2 and
green line at 0.7 which is for real part and all these lines coincide with
each other an the end and seems to be like one line but on the other
hand by looking at the imaginary part we can observe that initial point of
the three peaks formed by red,blue and green are at o but the peaks are
raising to 1.2 , 0.4 and 0.1 and then at end these three lines coincide
each other and merge with each other at the end .
Absortpiton Coefficient
By observing the figure , when the sillicon nanowire was not doped by
aluminum atoms then we can see the red line touching the 0.003 and we
can observe the simple plain line .By observing the graph , when the sillicon
nanowire was doped by 2 aluminum atoms then we can see the red line
touching the 0.003 and we can observe the little peak becoz of doping.By
observing the graph , when the sillicon nanowire was doped by 4 aluminumatoms then we can see the red line raising upwards and touching the 0.003
and we can observe the little peaks becoz of increase in doping .When the
sillicon nanowire was doped 6 aluminum atoms , the line starts at 0.004
and shows a rise in the peak till 0.006 and 0.008 and end line touches at
0.002 .By observing the graph , when the sillicon nanowire was not doped
by aluminum atoms then we can see the red line touching the 0.003 and
we can observe the simple plain line .By observing the graph , when the
sillicon nanowire was doped by 2 aluminum atoms then we can see the red
line touching the 0.003 and we can observe the little peak becoz of
doping.By observing the graph , when the sillicon nanowire was doped by 4
aluminum atoms then we can see the red line raising upwards and touching
the 0.003 and we can observe the little peaks becoz of increase in
doping.When the silliconnanowire was doped 6 aluminum atoms , the line
starts at 0.004 and shows a rise in the peak till 0.006 and 0.008 and end line
touches at 0.002 .
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
17/43
Sillicon Nanowire doped with 0,2,4,6 Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
18/43
Sillicon Nanowire doped with 0,2,4,6 P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
19/43
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
20/43
Band Structure analysis while doping with phosphorous atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
21/43
Optical Spectrum while doping of silicon atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
22/43
Optical Spectrum while doping of P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
23/43
Density of States while doping of Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
24/43
Density of states while doping of P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
25/43
Absorption Coefficient while doping of Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
26/43
Absorption Coefficeint while doping of P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
27/43
Titanium Nanowire
Bandstructure Analysis
By observing the figure , we can clearly say that when titanium is not
doped with any atoms still it shows metallic nature . Thats why the fermi
level is crossed by many lines. The last curve above the fermi level is at 0.01
and the last curve below the fermi level is -1.0 . There is no band gap which
shows it is metal .When titanium is doped by two aluminium atoms , then
metallic nature increases . The curve which is above the fermi level at 0.03and the curve which is below the fermi level is -0.013 . As usual there is no
band gap , still there crossing of lines in fermi level . This clearly shows the
doping nature .When titanium is doped by four aluminium atoms , then
metallic nature increases . The curve which is above the fermi level at 0.05
and the curve which is below the fermi level is -0.013 . As usual there is no
band gap , still there crossing of lines in fermi level . This clearly shows the
doping nature .When titanium is doped by six aluminium atoms , then
metallic nature increases . The curve which is above the fermi level at 0.01
and the curve which is below the fermi level is -0.012 . As usual there is no
band gap , still there crossing of lines in fermi level . This clearly shows the
doping nature .By observing the above graphs , we can clearly say that
when titanium is not doped with any atoms still it shows metallic nature .
Thats why the fermi level is crossed by many lines. The last curve above the
fermi level is at 0.01 and the last curve below the fermi level is -1.0 . There
is no band gap which shows it is metal .When titanium is doped by twophosphorous atoms , then metallic nature increases . The curve which is
above the fermi level at 0.03 and the curve which is below the fermi level is
-0.013 . As usual there is no band gap , still there crossing of lines in fermi
level . This clearly shows the doping nature .When titanium is doped by four
phosphorous atoms , then metallic nature increases . The curve which is
above the fermi level at 0.05 and the curve which is below the fermi level is
-0.013 . As usual there is no band gap , still there crossing of lines in fermi
level . This clearly shows the doping nature .When titanium is doped by six
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
28/43
phosphorous atoms , then metallic nature increases . The curve which is
above the fermi level at 0.01 and the curve which is below the fermi level is
-0.012 . As usual there is no band gap , still there crossing of lines in fermi
level . This clearly shows the doping nature . This graph clearly has lot of
dense lines crossing each other which shows it has maximum metallic
nature.
Density of states
By observing the figure , we can clearly say that when titanium is not
doped then , the graph which is at the middle of fermi level is 50 in the
density of states on y axis and there are around 2-3 little peaks near it .But
after doping the titanium nanowire with two aluminium atoms , then wecan see a decrease in the level of peak which turns out to be 45 on the
middle of fermilevel at density of states and peaks near it increase .But
after doping the titanium nanowire with four aluminium atoms , then we
can see a decrease in the level of peak which turns out to be 40 on the
middle of fermilevel at density of states and peaks near it increase .But
after doping the titanium nanowire with six aluminium atoms , then we can
see a decrease in the level of peak which turns out to be 35 on the middle
of fermilevel at density of states and peaks near it increase and becomes 5 .
We can clearly observe the decline by 5 times of fall is every doping .By
observing the figure , we can clearly say that when titanium is not doped
then , the graph which is at the middle of fermi level is 43 in the density of
states on y axis and there are around 2-3 little peaks near it .But after
doping the titanium nanowire with two phosphorous atoms , then we can
see a decrease in the level of peak which turns out to be 40 on the middle
of fermilevel at density of states and peaks near it increase .But afterdoping the titanium nanowire with four phosphorous atoms , then we can
see a decrease in the level of peak which turns out to be 35 on the middle
of fermilevel at density of states and peaks near it increase .But after
doping the titanium nanowire with six phosphorous atoms , then we can
see a decrease in the level of peak which turns out to be 30 on the middle
of fermilevel at density of states and peaks near it increase and becomes 5 .
We can clearly observe the decline by 5 times of fall is every doping .
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
29/43
Optical Spectrum
By observing the figure , here without doping the titanium ,we can clealry
see that blue line is missing and there is only presence of green and red line
. Green line is at 80 and red line is at 38 after that they coincide with eachother and merge themselves in the real part then in the imaginary part
there are two lines which are red and green that shows peak whose initial
point starts at zero and at end conincide each other and merge.By
observing the graph , after doping it with two aluminium atoms we can
clealry see that blue line is missing and there is only presence of green and
red line . Green line is at 50 and red line is at 40 after that they coincide
with each other and merge themselves in the real part then in the
imaginary part there are two lines which are red at 33 and green at 25 that
shows peak whose initial point starts at zero and at end conincide each
other and merge.By observing the graph , after doping with four aluminum
atoms ,we can clealry see that blue line is present and there is also
presence of green and red line . Red line is at 66 ,Green line is at 63and red
line is at 61 after that they coincide with each other and merge themselves
in the real part then in the imaginary part there are two lines which are red
, blue and green that shows peak at 40, 35 and 30 whose initial point startsat zero and at end conincide each other and merge.By observing the graph ,
after doping with six aluminum atoms we can clealry see that blue line is
present and there is only presence of green and red line . Green line is at 30
and red line is at 60 after that they coincide with each other and merge
themselves in the real part then in the imaginary part there are two lines
which are red and green that shows peak whose initial point starts at zero
and at end conincide each other and merge.By observing the above graphs ,
when titanium is not doped by any phosphorous atoms then red line is on
40 and green line is on 80 but on the case but on the other hand we can see
the imaginary part which has green line and red line whose initial point
starts with 0 and the peaks of the green line on 50 and red line on 20 . At
the other end , those lines coincide each other .By observing the above
graphs , when titanium is not doped by any phosphorous atoms then red
line is on 75 and green line is on 80 but on the case but on the other hand
we can see the imaginary part which has green line and red line whoseinitial point starts with 0 and the peaks of the green line on 35 and red line
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
30/43
on 10 . At the other end , those lines coincide each other .By observing the
above graphs , when titanium is not doped by any phosphorous atoms then
red line is on 50 and green line is on 25 but on the case but on the other
hand we can see the imaginary part which has green line and red line
whose initial point starts with 0 and the peaks of the green line on 50 and
red line on 10 . At the other end , those lines coincide each other .By
observing the above graphs , when titanium is not doped by any
phosphorous atoms then red line is on 45 , green line is on 89 and blue line
is on 25 but on the case but on the other hand we can see the imaginary
part which has green line and red line whose initial point starts with 0 and
the peaks of the green line on 60 , red line on 20 and blue line 10 . At the
other end , those lines coincide each other .
Absorption Coefficient
By observing the figure , we can say that ,When titanium isnot doped by
aluminium atoms , then we can see sharp curve in the graph which shows it
is not doped and there is no peak formation, the curve starts from 0 and
goes upwards.By observing the above graphs , we can say that ,When
titanium is doped by two aluminium atoms , then we can see some
distortion in sharp curve of graph and there is little peak formation, the
curve starts from 0 and goes upwards. This graph clearly shows variations
when it is doped little.By observing the above graphs , we can say that
,When titanium is doped by four aluminium atoms , then we can see many
distortion in sharp curve of graph and there is high peak formation, thecurve starts from 0 and goes upwards. This graph clearly shows variations
when it is doped .By observing the above graphs , we can say that ,When
titanium is doped by six aluminium atoms , then we can see distortions in
sharp curve of graph and there is no peak formation. But because of
extreme doping , it shows peculiar charecterstic , the intial and end point
changes and even peaks are depressed .By observing the above graphs , we
can say that ,When titanium isnot doped by phosphrous atoms , then we
can see sharp curve in the graph which shows it is not doped and there is
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
31/43
no peak formation, the curve starts from 0 and goes upwards.By observing
the above graphs , we can say that ,When titanium is doped by two
phosphrous atoms , then we can see some distortion in sharp curve of
graph and there is little peak formation, the curve starts from 0.005 and
goes downwards. This graph clearly shows variations when it is doped
little.By observing the above graphs , we can say that ,When titanium is
doped by four phosphorous atoms , we can see the peculiar charecterstics
like the curve starts by 0 and totally sticking to the x axis and from 500 it
rises above .By observing the above graphs , we can say that ,When
titanium is doped by six phosphorous atoms , then we can see distortions
in sharp curve of graph and there is no peak formation. But because of
extreme doping , it shows peculiar characteristic , the intial and end pointchanges and even peaks are depressed. This also resembles the extreme
doping of aluminium too.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
32/43
Titanium Nanowire doped by 0,2,4,6 Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
33/43
Titanium Nanowire doped by 0,2,4,6 p atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
34/43
Band structure analysis while doping of Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
35/43
Band structure analysis while doping of P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
36/43
Optical Spectrum while doped by Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
37/43
Optical Spectrum doped by P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
38/43
Density of states while doping with Al atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
39/43
Density of states while doped with P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
40/43
Absorption Coefficient while doped with Al atoms
.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
41/43
Absorption Coefficient while doped with P atoms
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
42/43
Refrences
Y. Wakayama, S. Tanaka, Surf. Sci. 1999, 420, 190.[118] E. I . Givargizov, Highly Anisotropic Crystals, Reidel, Dordrecht 1987.[119] B. Ressel, K. C. Prince, S. Heun, Y. Homma, J. Appl. Phys. 2003, 93, 3886.[120] G. A. Satunkin, V. A. Tatarchenko, Kristallografiya1985, 30, 772.[121] Y. A. Tatarchenko in, Shaped Crystal Growth, Kluwer Academic, Dordrecht1993, pp. 197206, Ch. 1.[122] V. Schmidt, S. Senz, U. Gosele, Appl. Phys. A 2005, 80, 445.[123] J. S. Rowlinson, B. Widom, Molecular Theory of Capillarity, Dover Publications,Mineola, NY 2002.[124] P. Chen, J. Gaydos, A. W. Neumann, Langmuir 1996, 12, 5956.[125] Y. V. Naidich, V. M. Perevertailo, L. P. Obushchak, Zh. Fiz. Khim. 1975, 49,1554.[126] R. J. Jaccodine, J. Electrochem. Soc. 1963, 110, 524.[127] S. C. Hardy, J. Cryst. Growth 1985, 71, 602.[128] M. Demeri, M. Farag, J. Heasley, J. Mater. Sci. Lett. 1974, 9, 683.[129] W. L. Falke, A. E. Schwaneke, R. W. Nash, Metall. Trans. B 1977, 8B, 301.[130] D. Giuranno, F. Gnecco, E. Ricci, R. Novakovic, Intermetallics2003, 11,1313.[131] W. Gasior, Z. Moser, J. Pstrus, J. Phase Equilib. 2003, 24, 504.[132] M. A. McClelland, J. S. Sze, Surf. Sci. 1995, 330, 313.
[133] K.-K. Lew, J. M. Redwing, J. Cryst. Growth 2003, 254, 14.[134] Y. Wu, R. Fan, P. Yang, Nano Lett. 2002, 2, 83.[135] J. Kikkawa, Y. Ohno, S. Takeda, Appl. Phys. Lett. 2005, 86, 123109.[136] H. Schmid, M. T. Bjork, J. Knoch, S. Karg, H. Riel, W. Riess, Nano Lett.2009, 9, 173.[137] V. Schmidt, S. Senz, U. Gosele, Phys. Rev. B 2007, 75, 045335.[138] T. Y. Tan, N. Li, U. Gosele, Appl. Phys. Lett. 2003, 83, 1199.[139] T. Y. Tan, N. Li, U. Gosele, Appl. Phys. A 2004, 78, 519.[140] F. Dhalluin, P. J. Desre, M. I. den Hertog, J. Rouvie`re, P. Ferret, P. Gentile,T. Baron, J. Appl. Phys. 2007, 102, 094906.[141] J. B. Hannon, S. Kodambaka, F. M. Ross, R. M. Tromp, Nature 2006, 440,69.[142] S. M. Sze, in: Physics of Semiconductor Devices, 2nd Edn., Wiley, New York1981.[143] J.-M. Zhang, F. Ma, K.-W. Xu, X.-T. Xin, Surf. Interface Anal. 2003, 35, 805.[144] P. M. Fahey, P. B. Griffin, J. D. Plummer, Rev. Mod. Phys. 1989, 61, 289.[145] H. Peelaers, B. Partoens, F. M. Peeters, Nano Lett. 2006, 6, 2781.
[146] V. Schmidt, H. Riel, S. Senz, S. Karg, W. Riess, U. Gosele, Small 2006, 2,85.[147] Y. H. Tang, T. K. Sham, A. Jurgensen, Y. F. Hu, C. S. Lee, S. T. Lee, Appl.Phys. Lett. 2002, 80, 3709.[148] N. Fukata, J. Chen, T. Sekiguchi, N. Okada, K. Murakami, T. Tsurui, S. Ito,
Appl. Phys. Lett. 2006, 89, 203109.[149] N. Fukata, J. Chen, T. Sekiguchi, S. Matsushita, T. Oshima, N. Uchida, K.Murakami, T. Tsurui, S. Ito, Appl. Phys. Lett. 2007, 90, 153117.[150] M. S. Gudiksen, L. J. Lauhon, J. Wang, D. C. Smith, C. M. Lieber, Nature2002, 415, 617.[151] C. Yang, Z. Zhong, C. M. Lieber, Science 2005, 310, 1304.[152] E. I. Givargizov, J. Cryst. Growth 1973, 20, 217.[153] K.-K. Lew, L. Pan, T. E. Bogart, S. M. Dilts, E. C. Dickey, J.M. Redwing, Y. F.Wang, M. Cabassi, T. S. Mayer, S. W. Novak, Appl. Phys. Lett. 2004, 85,3101.[154] Y. Cui, X. Duan, J. Hu, C. M. Lieber, J. Phys. Chem. B 2000, 104, 5213.[155] R. T. White, R. L. Espino-Rios, D. S. Rodgers, M. A. Ring, H. E. ONeal, Int.
J. Chem. Kinet. 1985, 17, 1029.[156] J. M. Jasinski, S. M. Gates, Acc. Chem. Res. 1991, 24, 9.[157] M. Diarra, Y. M. Niquet, C. Delerue, G. Allan, Phys. Rev. B 2007, 75,045301.[158] Y. M. Niquet, A. Lherbier, N. H. Quang, M. V. Fernandez-Serre, X. Blase,C. Delerue, Phys. Rev. B 2006, 73, 165319.[159] M. Diarra, C. Delerue, Y. M. Niquet, G. Allan, J. Appl. Phys. 2008, 103,073703.[160] M. T. Bjork, H. Schmid, J. Knoch, H. Riel, W. Riess, Nat. Nanotechnol.2009, 4, 103.[161] B. E. Deal, IEEE Trans. Electron Devices 1980, ED-27, 606.[162] M. H. White, J. R. Cricchi, IEEE Trans. Electron Devices 1972, ED-19, 1280.[163] Y. Nishi, Jpn. J. Appl. Phys. 1966, 5, 333.[164] Y. Nishi, Jpn. J. Appl. Phys. 1971, 10, 52.[165] Y. Nishi, A. Ohwada, K. Tanaka, Jpn. J. Appl. Phys. 1972, 11, 85.[166] D. L. Griscom, Phys. Rev. B 1980, 22, 4192.[167] P. J. Caplan, E. H. Poindexter, B. E. Deal, R. R. Razouk, J. Appl. Phys. 1979,
50, 5847.[168] P. M. Lenahan, P. V. Dressendorfer, Appl. Phys. Lett. 1982, 41, 542.[169] P. M. Lenahan, P. V. Dressendorfer, J. Appl. Phys. 1983, 54, 1457.[170] P. M. Lenahan, P. V. Dressendorfer, Appl. Phys. Lett. 1984, 44, 96.
-
8/13/2019 Electronic and Optical Properties of Sillicon and Titanium Nanowires
43/43
[171] Y. Y. Kim, P. M. Lenahan, J. Appl. Phys. 1988, 64, 3551.[172] N. M. Johnson, D. K. Biegelsen, M. D. Moyer, S. T. Chang, E. H.Poindexter, P. J. Caplan, Appl. Phys. Lett. 1983, 43, 563.[173] E. H. Poindexter, P. J. Caplan, B. E. Deal, R. R. Razouk, J. Appl. Phys. 1981,52, 879.[174] V. Schmidt, S. Senz, U. Gosele, Appl. Phys. A 2007, 86, 187.[175] K. I. Seo, S. Sharma, A. A. Yasseri, D. R. Stewart, T. I. Kamins, Electrochem.Solid-State Lett. 2006, 9, G69.
[176] I. Kimukin, M. S. Islam, R. S. Williams, Nanotechnology 2006, 17, S240.[177] E. B. Ramayya, D. Vasileska, S. M. Goodnick, I. I. Knezevic, J. Appl. Phys.2008, 104, 063711.[178] R. Kotlyar, B. Obradovic, P. Matagne, M. Stettler, M. D. Giles, Appl. Phys.Lett. 2004, 84, 5270.[179] D. Wang, B. A. Sheriff, J. R. Heath, Nano Lett. 2006, 6, 1096.[180] O. Gunawan, L. Sekaric, A. Majumdar, M. Rooks, J. Appenzeller, J. W.Sleight, S. Guha, W. Haensch, Nano Lett. 2008, 8, 1566.[181] Y. Wu, J. Xiang, C. Yang, W. Lu, C. M. Lieber, Nature 2004, 430, 61.[182] J. Goldberger, A. I. Hochbaum, R. Fan, P. Yang, Nano Lett. 2006, 6, 973.[183] Y. Cui, Z. Zhong, D. Wang, W. U. Wang, C. M. Lieber, Nano Lett. 2003, 3,149.[184] A. K. Buin, A. Verma, A. Svizhenko, M. P. Anantram, Nano Lett. 2008, 8,760.[185] X. Duan, C. Niu, V. Sahi, J. Chen, J. W. Parce, S. Empedocles, J. L.Goldman, Nature 2003, 425, 274.[186] S. Jin, D. Whang, M. C. McAlpine, R. S. Friedman, Y. Wu, C. M. Lieber,Nano Lett. 2004, 4, 915.[187] T.-T. Ho, Y. Wang, S. Eichfeld, K.-K. Lew, B. Liu, S. E. Mohney, J. M.Redwing, T. S. Mayer, Nano Lett. 2008, 8, 4359.[188] G. Zheng, W. Lu, S. Jin, C. M. Lieber, Adv. Mater. 2004, 16, 1890.[189] M. T. Bjork, O. Hayden, H. Schmid, H. Riel, W. Riess, Appl. Phys. Lett.2007, 90, 142110.[190] M. T. Bjork, J. Knoch, H. Schmidt, H. Riel, W. Riess, Appl. Phys. Lett. 2008,92, 193504.[191] L. J. Lauhon, M. S. Gudiksen, D. Wang, C. M. Lieber, Nature 2002, 420,57.