A Monte Carlo Study of $\hbox{Hg}_{0.7}\hbox{Cd}_{0.3}\hbox{Te}$ e-APD

A simple Monte Carlo model is developed for understanding the multiplication process in HgCdTe infrared avalanche photodiodes and the impact of physical and technological parameters. A good agreement is achieved between simulations and experimental measurements of gain and excess noise factor. In both cases, an exponential gain and extremely low noise—$F \sim \hbox{1}$ for multiplication gains up to 1000—were observed on 5.1-$\mu\hbox{m}$ cutoff devices at 77 K, indicative of a single carrier impact ionization. A comparison study is presented to explain the effect of different combinations of scattering processes on the avalanche phenomenon in HgCdTe.