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Optical Engineering

Modeling of midwavelength infrared InAs/GaSb type II superlattice detectors
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Paper Abstract

The performance of midwavelength infrared type II superllatice InAs/GaSb PIN and nBn (AlGaSb barrier) photodetectors in a reverse bias voltage range and a temperature range from 77 to 240 K is described. The PIN and nBn structures are modeled by a bulk based model, i.e., type II superllatice is treated as an artificial semiconductor material where parameters describing its physical properties are extracted from the experimental data. The model assumes that position of the effective trap energy level depends on temperature, what allowed to obtain a very good fitting to the measurements. Temperature and bias dependent dark current and differential resistance area product of the both devices have been analyzed to investigate contributing mechanisms such as: diffusion, generation-recombination, band-to-band and trap-assisted tunneling that limit the electrical performance of both types of the detectors. The I−V and RA(V) product characteristics of both types of type II superllatice InAs/GaSb photodetectors were found to be dominated by diffusion and generation-recombination currents in the nearly zero-bias region. At medium values of reverse bias, the trap-assisted tunneling reveals its significance, while at higher reverse voltages—the band-to-band tunneling is decisive to I−V and RA(V) characteristics. The fitting procedure allowed to extract both generation-recombination and diffusion components of carrier lifetimes pointing out that the carrier lifetimes range from 2 to 10 ns at T=200  K . Detectivity for T=240  K and V=50  mV was estimated to be 10 9   cmHz 1/2 /W and 4×10 9 cmHz 1/2 /W for PIN and nBn detector, respectively. Finally, type II superlattice InAs/GaSb PIN and nBn structures’ performance is compared to both unipolar barrier nBn HgCdTe detector and bulk HgCdTe photodiodes operated at near-room temperature. It is shown that the performance of SL and HgCdTe photo detectors with a cut-off of about 5 μm is comparable at operation temperatures around 240 K.

Paper Details

Date Published: 31 January 2013
PDF: 13 pages
Opt. Eng. 52(6) 061307 doi: 10.1117/1.OE.52.6.061307
Published in: Optical Engineering Volume 52, Issue 6
Show Author Affiliations
Piotr Martyniuk, Military Univ. of Technology (Poland)
Jaroslaw Wrobel, Military Univ. of Technology (Poland)
Elena Plis, Ctr. for High Technology Materials (United States)
Pawel Madejczyk, Military Univ. of Technology (Poland)
Waldemar Gawron, Military Univ. of Technology (Poland)
Andrzej Kowalewski, Military Univ. of Technology (Poland)
Sanjay Krishna, Ctr. for High Technology Materials (United States)
Antoni Rogalski, Military Univ. of Technology (Poland)

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