Unipolar barrier-integrated HgCdTe infrared detectors

Abstract

HgCdTe-based infrared (IR) detectors remain the front-runner for high performance IR focal plane array (FPA) applications due to their favorable material and optical properties. While state-of-the-art HgCdTe p-n junction technology such as the double layer planar heterostructure (DLPH) devices can achieve near theoretical performance in the mid-wave and long-wave infrared (MWIR, LWIR) spectral ranges, the cryogenic cooling requirements to suppress dark current are still much greater than desired. HgCdTe material growth by molecular beam epitaxy (MBE) provides the accurate control over alloy composition and doping required to achieve future detector architectures that may serve to reduce dark current for enhanced operation. However, controllable in situ p-type doping of HgCdTe by MBE is still problematic. As a potential solution to address these issues, we propose a unipolar, type-I barrier-integrated HgCdTe nBn IR detector based on similar principles to the type-II nBn structure used in III–V materials [1] with the intent that it may serve as a basis for advanced HgCdTe-based architectures for reduced cooling requirements.