Mid-IR focal plane array based on type-II InAs∕GaSb strain layer superlattice detector with nBn design

Abstract

A midwave infrared camera (λc=4.2μm) with a 320×256 focal plane array (FPA) based on type-II InAs∕GaSb strain layer superlattice (SLs) has been demonstrated. The detectors consist of an nBn heterostructure, wherein the SL absorber and contact layers are separated by a Al0.2Ga0.8Sb barrier layer, which is designed to have a minimum valence band offset. Unlike a PN junction, the size of the device is not defined by a mesa etch but confined by the lateral diffusion length of minority carriers. At 77K, the FPA demonstrates a temporal noise equivalent temperature difference (NETD) of 23.8mK (Tint=16.3ms and Vb=0.7V) with a peak quantum efficiency and detectivity at 3.8μm equal to 52% and 6.7×1011 Jones, respectively.