%0 Journal Article
%T InAs/GaSb Type-II Superlattice Detectors
%A Elena A. Plis
%J Advances in Electronics
%D 2014
%R 10.1155/2014/246769
%X InAs/(In,Ga)Sb type-II strained layer superlattices (T2SLs) have made significant progress since they were first proposed as an infrared (IR) sensing material more than three decades ago. Numerous theoretically predicted advantages that T2SL offers over present-day detection technologies, heterojunction engineering capabilities, and technological preferences make T2SL technology promising candidate for the realization of high performance IR imagers. Despite concentrated efforts of many research groups, the T2SLs have not revealed full potential yet. This paper attempts to provide a comprehensive review of the current status of T2SL detectors and discusses origins of T2SL device performance degradation, in particular, surface and bulk dark-current components. Various approaches of dark current reduction with their pros and cons are presented. 1. Introduction Since proposed in 1980s [1每3], the InAs/(In,Ga)Sb T2SL has gained a lot of interest for the infrared (IR) detection applications. Focal plane arrays (FPAs) based on T2SL and operating in mid-wave IR (MWIR, 3每5ˋ米m) and long-wave IR (LWIR, 8每12ˋ米m) are of great importance for a variety of civil and military applications. Currently market dominating technologies are based on bulk mercury cadmium telluride (MCT) and InSb [4每6], and GaAs/AlGaAs quantum well IR photodetectors (QWIPs). While MCT detectors have very large quantum efficiency (>90%) and detectivity, they are still plagued by nonuniform growth defects and a very expensive CdZnTe substrate that is only available in limited quantities by a foreign manufacturer. There has been significant progress on development of MCT on silicon substrates, but good performance has been limited to the MWIR band only. Moreover, MCT is characterized by low electron effective mass resulting in excessive leakage current [7]. The InSb detectors do not cover the LWIR spectral range. QWIPs are based on III-V semiconductors and their mature manufacturing process enables them to be scaled to large format FPAs with a high degree of spatial uniformity [8每10]. However, due to polarization selection rules for electron-photon interactions in GaAs/AlGaAs QW, this material system is insensitive to surface-normal incident IR radiation resulting in poor conversion quantum efficiency, In addition, their large dark currents lower the operating temperature and increase the operating cost of the imager. The development of FPAs based on mature III-V growth and fabrication technology and operating at higher temperatures will result in highly sensitive, more reliable, lighter, and less
%U http://www.hindawi.com/journals/aelc/2014/246769/