Photoconductive gain in barrier heterostructure infrared detectors

Stephen Myers; Brianna Klein; Elena Plis; Nutan Gautam; Chris Morath; Vincent Cowan; Sanjay Krishna

doi:10.1117/12.919648

31 May 2012 Photoconductive gain in barrier heterostructure infrared detectors

Stephen Myers, Brianna Klein, Elena Plis, Nutan Gautam, Chris Morath, Vincent Cowan, Sanjay Krishna

Proceedings Volume 8353, Infrared Technology and Applications XXXVIII; 83532Z (2012) https://doi.org/10.1117/12.919648
Event: SPIE Defense, Security, and Sensing, 2012, Baltimore, Maryland, United States

Abstract

Infrared (IR) detector technologies with the ability to operate near room temperature are important for many applications including chemical identification, surveillance, defense and medical diagnostics. Reducing the need for cryogenics in a detector system can reduce cost, weight and power consumption; simplify the detection system design and allow for widespread usage. In recent years, infrared (IR) detectors based on uni-polar barrier designs have gained interest for their ability to lower dark current and increase a detector's operating temperature. Our group is currently investigating detectors based on the InAs/GaSb strain layer superlattice (SLS) material system that utilize barrier heterostructure engineering. Examples of such engineering designs include pBp, nBn, PbIbN, CBIRD, etc. For this paper I will focus on LW (long wave) pBp structures. Like the built-in barrier in a p-n junction, the heterojunction barrier blocks the majority carriers allowing free movement of photogenerated minority carriers. However, the barrier in a pBp detector, in contrast with a p-n junction depletion layer, does not significantly contribute to generation-recombination (G-R) current due to the lack of a depletion region across the narrow band gap absorber material. Thus such detectors potentially work like a regular photodiode but with significantly reduced dark current from G-R mechanisms. The mechanism of photoconductive (PC) gain has not been fully characterized in such device architectures and in many recent studies has been assumed to be unity. However, studies conducted with similar device structures have shown the presence of PC gain. In this report we will measure and analyze the impact of PC gain in detectors utilizing single unipolar barriers such as the case of pBp detectors.

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Stephen Myers, Brianna Klein, Elena Plis, Nutan Gautam, Chris Morath, Vincent Cowan, and Sanjay Krishna "Photoconductive gain in barrier heterostructure infrared detectors", Proc. SPIE 8353, Infrared Technology and Applications XXXVIII, 83532Z (31 May 2012); https://doi.org/10.1117/12.919648

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KEYWORDS

Sensors

Infrared detectors

Absorption

Superlattices

Infrared sensors

Infrared radiation

Infrared technology

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