Two-dimensional modelling of HgCdTe photoconductive detectors

The performance of n-type HgCdTe mid-wavelength infrared (MWIR) photoconductors has been investigated using two-dimensional (2-D) device modelling. A comparison has been made between a practical detector structure with planar contacts on the upper HgCdTe surface, and a structure commonly used in one-dimensional (1-D) device modelling with end contacts to the photo-absorbing slab of semiconductor. This comparison highlights differences in detector responsivity, and spatial distribution of both the applied electric field and photogenerated minority carriers. The practical device structure, where 2-D effects are most evident, provided a good fit to experimental results for frontside-illuminated n-type HgCdTe photoconductive detectors with n(+)/n blocking contacts without needing to include S, the contact recombination velocity, which is commonly employed in 1-D models as a fitting parameter. Instead, only the n(+) doping density (1 x 10(16) cm(-3)) and n(+) doping region (depth of 3 mu m), were used to account for the partial blocking of minority carriers by the contact region. In addition, the 2-D model was used to examine the influence of n(+) blocking contact geometry and doping density on n-type HgCdTe photoconductor responsivity performance. (C) 2000 Elsevier Science B.V. All rights reserved.