Performance and stability of HgCdTe photoconductive devices: a study of passivation and contact technology

HgCdTe is the material of choice for high performance infrared (IR) detectors operating in the long-wavelength and mid-wavelength (LWIR and MWIR, respectively) regions of the electromagnetic spectrum. Photoconductive HgCdTe IR detectors are commonly used for single element and linear arrays due to their higher yield when compared to photovoltaic devices. In this work characterisation of fabricated n-type photoconductors with blocking contacts and heterostructure passivation are presented. The two-layer heterostructure photoconductors exhibit up to a 100% increase in responsivity over the equivalent single-layer photoconductors at an applied electric field of 10 V/cm. The two-layer and single-layer photoconductors have been subjected to bake tests at 85°C for 20 hours with the single-layer photoconductors showing a large degradation in performance compared to the two-layer photoconductors. A suitably modified commercial device simulation package has been used to model blocking contacts in two dimensions