Numerical estimation of photon reabsorption process and optical crosstalk in arrays of HgCdTe photodiodes

Abstract

The effect of photon reabsorption (recycling) on photoelectric parameters of non-equilibrium P+nN+ photodiodes, for example the pixels of the detector array, was analyzed. We solved the system of transport equations additionally extended by two balances equations for photons. It was shown that the density of photons in photodiodes is strongly dependent on the concentration of charge carriers. This phenomenon results in a drastic reduction in the rate of radiative recombination and generation in analyzed photodiodes. Additionally, the phenomenon of optical crosstalk between the nearest pixels in the matrix was examined. The increase in the dark current caused by this phenomenon was estimated. It depends on the size of the pixel, the distance between pixels, and the value of bias voltage. The increase in the current is around 0.5% for a pixel with surface 10 × 10 µm2, and around 1% for one with 5 × 5 µm2, both reverse biased with 0.2 V.