Drc 2010 D.J.Pawlik

Sub-Micron InGaAs Esaki Diodes With

Record High Peak Current Density

D. Pawlik, M. Barth, P. Thomas,

S. Kurinec, S. Rommel

S. Mookerjea, D. Mohata, S. Datta

S. Cohen, D. Ritter

Device Research Conference: June 22, 2010

This work is partially supported by NSF (ECCS-0725760)

D. J. Pawlik DRC: June 22, 2010 2/20

Key Metrics

Peak Current: JP = IP/Area

Valley Current: JV = IV/Area

Peak-to-Valley current ratio: PVCR

n+++ -ip++

-0.5 0.0 0.5

10-1

100

101

102

TD1

TD2

Cu

rre

nt

De

nsity (

mA

/m

2)

Voltage (V)

Record High

Current Density

JP

JV

JZ

VP VV

Esaki Tunnel Diode (ETD)

1

2

12

*

*

exp

exp

P d

A Dd

A D

P

J w

N Nw N

N N

J N

-

-

-

+

-


Applications

Gated “p-i-n” Esaki diode

Operated in Zener direction

High JZ needed for drive current

Scaled to deep sub-micron dimensions

n++

Source

Drain

i

P++

Gat

eTunneling FET (TFET)

Multijunction Solar Cells Tunneling SRAM BJT & Contacts

website:www.sustainability.rit.edu/nanopower/

Word Line

VCC

Bit Line VSN

I

VCC

VSN

Word Line

VCC

Bit Line VSN

Word Line

VCC

Bit Line VSN

I

VCC

VSN

I

VCC

VSN

Tunnel

Diodes

E. Yalon, et Al., DRC 2010

Tunnel

Junction


Scaling D. J. Pawlik, et al., ISDRS 2009

100

101

102

103

104

10

15

20

PV

CR

Mask Defined Area (m2)

PVCR(max)

PVCR(Ave)

Max. PVCR improved with area

What about current density?


InGaAs Tunnel Diodes

MBE Grown at IQE

Higher level of doping than TD2

Contact layers: reduced doping

MOMBE Grown at Technion,

Haifa, Israel

Lower Doping than TD1

Contact layers; high doping

1. JTD1 > JTD2

2. RTD1 > RTD2

Predictions:

TD1 TD2


200 nm

200 nm

Fabrication Process

Metal 1

Defined by E-Beam lithography

Au/Zn/Au (20nm/20nm/160nm)

Mesa Isolation Etch

Citric Acid : H2O2 (20:1)

~80 nm deep

~20 nm below the junction


Device Area Characterization

Mask Defined Radius = 100nm

Extensive SEM analysis needed

Critical for accurate analysis


(3) Contact pads Final Structure

(1) Metal and Mesa (2) BCB Etch back

200 nm

Junction

Location

Metal 1

(Gold)

40 m

Fabrication (Continued)


-0.50 -0.25 0.00 0.25 0.50 0.75 1.00

10-5

10-4

10-3

10-2

10-1

TD2 (m2)

0.693

0.315

0.111

0.0461

TD1 (m2)

4.38

1.55

0.694

Cu

rre

nt

(A)

Voltage (V)

Electrical Characterization

Large area ETD as virtual ground

~25,200 m2

Current Scales with area

PVCRTD2 > PVCRTD1

JTD1 > JTD2

Ground Connection:

Preliminary Results


64 128 256 512 10240.0

0.2

0.4

0.6

0.8

1.0

1.2

TD1

No

rmali

zed

Co

un

tJ

P (kA/cm

2)

TD2

Area Scaling & Current Density

Area scaling of IP JP Histogram

Current scales linearly with area

Deviations from trendline are

likely due to uncertainties in area

Devices measured: 200+ each

Gaussian fit used to determine JP

As predicted JTD1 > JTD2

10-2

10-1

100

101

10-5

10-4

10-3

10-2

TD1

P: 5 x 1019

cm-3

N: 5 x 1019

cm-3

TD2

P: 5 x 1019

cm-3

N: 5 x 1019

cm-3

slop

e = 2

.2 m

A/

m2

I P (

A)

Area (m2)

slop

e = 1

0 m

A/

m2

JP

(mA/m2)

s

(mA/m2)

s

(%)

TD1 9.75 90.2 9.3

TD2 2.10 17.5 8.3

Record high current density !!


1 10 100

10-4

10-3

10-2

10-1

100

101

102

Franks, 1965

Eberl, 2001

Chung, 2006

Wang, 2

003Ismail, 1993

See, 2001

Rommel, 1998

Franks, 1965

Holonyak, 1960Richard, 1993

Smet, 1993

Day,1993

Tsai, 1994

Broekaert,1989

Cohen, 1995

Rommel 08

Rommel 08

Rommel 08

Rommel 08

This work

This work

Si Substrate

GaAs Substrate

InP Substrate

GaAs on Si

JP (

mA

/m

2)

PVCR

Richard, 1993

Holonyak, 1960

Area Scaling & Current Density


Current Density vs. N*

*

*

exp

1exp

P d

P

A D

A D

J w

JN

N NN

N N

-

-

+


-0.50 -0.25 0.00 0.25 0.50 0.75 1.0010

-1

100

101

Cu

rre

nt

(mA

/m

2)

Voltage (V)

4.38 m2

0.694 m2

~ 8

RS introduces voltage shift

Effects: Apparent (false) reduction in JZ

Smaller currents result in smaller shifts

Smaller junctions have are effected by RS less

Series Resistance (RS)

2.5x~0.3 V


10-5

10-4

10-3

10-2

0.00

0.25

0.50

0.75

TD2

VP = 1.65() x I

P + 0.137(V)

TD1

TD2

VP (

V)

IP (A)

VP = 7.84() x I

P + 0.377(V)

TD1

Series Resistance: Constant

Types of RS:

(1) Constant (RC)

Provides linear change in

VP(Meas) with respect to

RC is the slope of VP vs. IP

(2) Area dependent (rArea)

( ) .

( .)

AreaP Measured P P Const

P Meas C P P A P

V V I RArea

V R I J V

r

r

+ +

+ +

y = m * x + b


0 5 10 15 20

-150

-100

-50

0

50

100

V -1 (2

.5 m

A)

V -1

(-30 mA)

V -1(-5 mA)

V -1(-2

50

A)

V -

1 (800

A)

Slope = m (1/V-m2)

VI-1

Area (m2)

V -

1 (15

0

A)

-0.50 -0.25 0.00 0.25 0.50 0.75

10-5

10-4

10-3

10-2

10-1

84 nm

127 nm

189 nm

297 nm

518 nm

746 nm

1,053 nm

1,545 nm

2,029 nm

2,505 nm

V5

V4

V3

V2

Cu

rre

nt

(A)

Voltage (V)V1

-30 -20 -10 0 10

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

TD2

1/s

lop

es (

V*

m2)

Current (mA)

TD1

Series Resistance: Area Dependant

For a constant current (IC);

RC constant V shift

rA variable V shift

TD2: I-V Curves Constant Current Curves Specific Resistivity

TD C C AV V I R Ar + +

TD1 TD2

rA (-m2) 76.2 41.9

b (mV-m2) 212 1.99

11

A CV I Ar--

A CV A I br +

y m * x y = m * x + b


Conclusion

Extensive SEM measurements needed to

characterize junction areas.

Junctions as small as ~0.015 m2 (R = 69 nm)

were fabricated.

Degradation of JP and JZ were not directly

observed

Sub-micron junctions needed to minimize

RSeries effects

RSeries was characterized

Highest reported JP of 9.75 mA/m2 for any

tunnel diode was measured

Drc 2010 D.J.Pawlik

Documents

Transcript of Drc 2010 D.J.Pawlik