Electrical characteristics of MOVPE grown MWIR N+p(As)HgCdTe heterostructure photodiodes build on GaAs substrates

Well recognized are the potential benefits in camera simplicity, power reduction and increased cooler life associated with the capability of operating infrared focal plane arrays at or near room ambient temperatures. Quality imagery in the 3 to 5 μm spectral band at scene temperature of 300K with focal plane array temperatures up to 175K was demonstrated recently. The array consisted of 640*512, 16 μm pitch N+p(As) detector elements grown by metal organic vapor phase epitaxy on a GaAs substrate. In this paper, a carrier recombination model is presented that explains the dark current density data as a function of inverse temperature. Basically the dominant carrier recombination occurs through ionized donor-like flaws centered in the upper half of the energy gap. For Hg1-xCd x Te, x=0.3 and 0.2867 materials, the flaw energy level, Eflaw(0K) respectively, is centered at 0.189 eV and 0.1181 eV above the valence band edge; The shortest possible lifetime τp0 for hole capture respectively is 3.5 and 550 μs. Band to band recombination is not observed to be dominant even in the temperature region T ≈ 300K, where the radiative and Auger lifetimes are significantly smaller than τp0. The asymmetry parameter γ = τn0/τp0 <<1.