Oct 14th – 16th 2015, Brno, Czech Republic, EU
ELECTRICAL PERFORMANCE OF INAS/ALSB/GASB SUPERLATTICE PHOTODETECTOR
M. Hostut 1*, T. Tansel 3,Y. Ergun3, A. Kilic 3, A. Aydinli4
1
Akdeniz University Department of Physics Education, Antalya,
2 Hacettepe
3Anadolu
University Nuclear Science Institute, Ankara,
University Physics Department, Eskişehir,
4 Bilkent
University Physics Department, Ankara
Abstract
Temperature dependent of dark current measurement is an efficient way to verify the quality of an infrared
detector. Low dark current density values are needed for high performance detector applications.
Identification of dominant current mechanism in each operating temperature with extracted their minority
carrier lifetimes are highly important for understanding of carrier transport and improve the detector
performance. Here we present electrical as well as optical performance of InAs/AlSb/GaSb based type-II SL
N-structure photodiodes
Keywords: Superlattice, dark current, detectivity, GaSb/InAs Infaraed detectors, Introduction
N-Structure GaSb/AlSb/InAs superlattice structure is offered at 2012[1]. Authors Show that if AlSb is placed
between InAs and GaSb interface(single site but first interface in one period when structure is growing), ehh overlap incrase when bias is reversed. AlSb mono layers affects as a electron barier to supress forward
difusion current also. In this work we investigated current voltage characteristic an their current components
at differen temperatures. Thus, current density-voltage (J-V) characteristics of InAs/AlSb/GaSb based type-II
SL N-structure photodiodes are measured as a function of temperature (78-271K). The J-V curves are fitted
by using Shockley Formula in order to identify the dominant dark current mechanizm in each operating
temperature range. Minority carrier lifetimes are extracted from temperature dependence of current density
(J-1000/T) curve quantatively [3]. While Fig.1 shows N –Structure real space band profile Fig.2 shows also
band profile but under external applied voltage(reverse bias). Fig.3 a and b Show I-V characteristic obtained
different temperature and obtained activation energy which is suitable e-hh optical transition energy. On the
other hand, Fig.4 is responsivity calculated by optical response and dark current experiments. Fig.5 also
Show current compenents ant their time constants obtained by simulation studies.
Fig.1 (a) Layer sequence in growth
direction, (b) conduction and valence band
profiles for asymmetric InAs/AsSb/GaSb
based T2SL N-structure
Fig.2 Conduction and valence band
profiles for N-structure with electron and
hole confinement under reverse bias
Oct 14th – 16th 2015, Brno, Czech Republic, EU
1
1
J (-100mV) Exp
0.1
2
Dark Current Density (A/cm )
0.1
271K
245K
215K
189K
160K
140K
125K
113K
102K
87K
0.01
1E-3
1E-4
1E-5
1E-6
Diff Lim
GR Lim
0.01
1E-3
Eg=0,270eV
Eg/2=0,135eV
1E-4
1E-5
1E-6
1E-7
1E-7
1E-8
1E-8
1E-9
1E-9
-0.4
-0.2
0.0
0.2
0.4
4
V (V)
6
8
10
12
1000/T (1/K)
Fig. 3 (a) Temperature dependence of dark current density, (b) Arrhenius plot of dark current density vs
inverse temperature (1000/T).
Energy (eV)
0,40
0,4
0,38
0,36
0,34
0,32
0,30
0,28
79K
Experimental data
Varshni Fit
0,2
0,28
Eg (eV)
R (A/W)
0,30
0,26
Eg(T)=Eg(0)-[T2/()]
0,24
0,22
50
Eg(0)=288 meV
=0.41 meV/K
=500 K
100
0,0
3,0
3,2
3,4
150
200
T (K)
3,6
250
3,8
300
4,0
4,2
4,4
4,6
Wavelength (m)
Fig.4: Responsivity spectrum of N-Structure at 79K. Inset shows Varshni fit for band gap energy extracted
from optical response spectra for different temperatures.
Oct 14th – 16th 2015, Brno, Czech Republic, EU
JDIFF
JGR
JTOT
-1
JExp.
2
Current density (A/cm )
10
Diff. life time
GR life time
e=2ns
GR=25ns
10
-2
(ns)
10
-3
10
-4
10
a
T=160K
-0.4
0
1
b
6
0.4
Voltage (V)
9
12
-1
1000/T (K )
Fig.5 (a) -Experimental JExp. (solid line) and modelled JDIFF (yellow dot), JGR (green dot) and JTOT total dark
current densities versus voltage of N-structure SL photodiode at T = 160 K (a) and T = 200 K. (b) -Calculated
diffusion (e) and GR ( ) lifetimes at various temperatures.
GR
CONCLUSION
Temperature dependence of J–V characteristics is analysed in InAs/AlSb/GaSb based T2SL N-structure.
Deduced from J–V curve-fitting, minority carrier lifetimes have been estimated in the temperature range 87–
215 K. At 87K and under -0.1V bias voltage, the dark current density is measured as 9.29x 10 -8 A/cm2 and
corresponding dynamic resistance area product (RA) is determined as 6.43x10 5Ωcm2. In the temperature
range 271–125 K, the dark current density reveals diffusion-limited behavior (Arrhenius type) with electron
lifetime values between 1ns and 15ns. In the lower temperature range (125–87 K), the dominant mechanism
starts to become generation recombination (GR) with GR lifetimes varies between 16-20ns.
ACKNOWLEDGEMENTS
Y.Ergun and A. Kilic acknowledges the supports of Anadolu University (BAP Grant: 13005F108)
REFERENCES
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