Bias dependence of photo-response in HgCdTe photodiodes due to series resistance

Abstract

In this paper, we present the experimental results of photo-response measurements performed on Hg 0.7Cd 0.3Te photodiodes and report the dependence of measured quantum efficiency on the applied bias. Because of non-zero series resistance of a photodiode, the apparent photo-response may lower down at near zero bias region of operation or near the bias of peak dynamic resistance, which is the preferred bias. By increasing the reverse bias we may compensate this reduction but only up to a certain reverse voltage. Beyond this limit, the dynamic resistance of the photodiode reduces due to tunneling current, resulting in the reduction in apparent photo-response. Due to this behavior a peak appears in the measured quantum efficiency when plotted against the applied reverse bias voltage in contrast to the view that quantum efficiency is independent of bias.