HgCdTe has dominated the high performance end of the IR detector market for decades. At present, the fabrication costs
of HgCdTe based advanced infrared devices is relatively high, due to the low yield associated with lattice matched
CdZnTe substrates and a complicated cooling system. One approach to ease this problem is to use a cost effective
alternative substrate, such as Si or GaAs. Recently, GaSb has emerged as a new alternative with better lattice matching.
In addition, implementation of MBE-grown unipolar n-type/barrier/n-type detector structures in the HgCdTe material
system has been recently proposed and studied intensively to enhance the detector operating temperature. The unipolar
nBn photodetector structure can be used to substantially reduce dark current and noise without impeding photocurrent
flow. In this paper, recent progress in MBE growth of HgCdTe infrared material at the University of Western Australia
(UWA) is reported, including MBE growth of HgCdTe on GaSb alternative substrates and growth of HgCdTe nBn
A theoretical calculation result of Hg1-xCdxTe (x=0.3) avalanche photodiodes (APDs) based on PIN structure is
obtained in the paper, which has a ratio of ionization factor k=0.06. The energy dispersion factor and the threshold
energy are acquired according to the parameters of material. And the gain, as well as the breakdown voltage, is obtained.
The composition, thickness, doping level is calculated theoretically to get an optimized APD device.