Analysis of dark current in long-wavelength HgCdTe junction diodes at low temperature and an approximate method to calculate the trap density of depletion region

Abstract

This paper analyzes the dark current characteristic of two different sizes at different temperature. The wavelength is 12 μm. We find that the main mechanism of the dark current is band-to-band tunnel current at 20 k-30 k. By fitting the ideal factor, we find that at temperature of 80 k-100 k, the dark current is a mixture of diffusion current, g-r current. We find the large size is better by comparing the R₀A-V curves. At 45 k-60 k, the dark current is a mixture of trap-assisted tunnel current and band-to-band tunnel current. An interesting thing is that in this temperature area, the different R₀-V curves have a same sharp cross which does not exist in the 20 k-30 k area or 80 k-100 k area. At this point the trap-assisted tunnel is equal to the band-to-band tunnel. We calculated the trap density of depletion region which is about 1.38×10¹¹ cm^-3 at 55 k.