HOT InAs/InAsSb nBn detector development for SWaP detector

Abstract

High operating temperature(HOT) is the key for low size, weight and power(SWaP) detector development and SWaP detector is the key for modern weapon system such as unmanned aerial vehicle(UAV) and man portable system. The low dark current that determines the operating temperature can be achieved by adopting InAs/InAsSb type-II superlattice(T2SL) absorber and nBn structure. In this work, HOT mid-wavelength infrared(MWIR) detector with InAs/InAsSb T2SL absorber and AlAsSb barrier was developed. The AlAsSb barrier shows excellent lattice match with GaSb substrate. Only the dry etch for pixel reticulation was applied to fabricate the device. At 80 K, dark current density is 2e-9 A/cm2 at the bias -0.2 V and, at 130 K, 2e-7 A/cm2 at the bias -0.1 V. The quantum efficiency was measured for both front side illumination and back side illumination. The back side illumination offers higher quantum efficiency than the front side illumination. The average quantum efficiency is about 50 % for front side illumination with 3 μm absorber. The 640 x 512 VGA format focal plane array(FPA) with 15 μm pitch was fabricated to study the temperature dependency of electro-optical characteristics. It was found that mean noise equivalent temperature difference(NETD) below 150 K is 15 mK, which is limited by the well capacitance. As the temperature increases NETD increases proportional to the dark current.