A highly strained InAs/GaSb type II superlattice for LWIR detection

Yiqiao Chen; Aaron Moy; Kan Mi; Wentao Lu; Peter Chow

doi:10.1117/12.2025514

24 September 2013 A highly strained InAs/GaSb type II superlattice for LWIR detection

Yiqiao Chen, Aaron Moy, Kan Mi, Wentao Lu, Peter Chow

Proceedings Volume 8876, Nanophotonics and Macrophotonics for Space Environments VII; 887610 (2013) https://doi.org/10.1117/12.2025514
Event: SPIE Optical Engineering + Applications, 2013, San Diego, California, United States

Abstract

IR photo detectors are in high demand for various military and civilian applications, such as airborne surveillance, remote sensing, environmental monitoring, and spectrometry. Recently InAs/GaSb type II superlattice (T2SL) has attracted numerous R and D interest since SLS is the only IR material that has a theoretical prediction of higher performance than HgCdTe. Here we report the improvement of SL photo diodes through a new design with highly-strained type-II superlattice (HS-T2SL). The HS-T2SL consists of a highly compressively strained thick InSb layer at InAs/GaSb interfaces. The presence of coherent strain shifts the band edges such that the SL energy gap is reduced. This reduced band gap is advantageous to photodetectors because longer cut-off wavelengths can be obtained with reduced layer thickness in the strained SL. The highly compressive strain in HS-T2SL also leads to an even higher optical absorption coefficient and lower dark current. Applying this new design resistance-area product (R₀A) is measured as high as 2.1 Ohm-cm² at 85K for 14.8-μm-cutoff photo diodes without any dark current suppression barriers. The fabricated 14.5μm-cutoff photo diode shows Johnson-noiselimited peak detectivity of 8.4×10¹⁰ cmHz^1/2/W at zero bias at 85K.

Citation Download Citation

Yiqiao Chen, Aaron Moy, Kan Mi, Wentao Lu, and Peter Chow "A highly strained InAs/GaSb type II superlattice for LWIR detection", Proc. SPIE 8876, Nanophotonics and Macrophotonics for Space Environments VII, 887610 (24 September 2013); https://doi.org/10.1117/12.2025514

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