Multi-parameter study on the performance fluctuation of InGaAsP/InP single photon avalanche diodes

To reveal the detailed correlation between the controllability of structure parameters in fabrication process and the homogeneity of device performance of single photon avalanche diodes (SPADs), simulations on multi-parameter fluctuations are carried out. We find that, for typical InGaAsP/InP SPADs, significant fluctuation of structure parameters cause asymmetry distribution of the dark count rate (DCR). The asymmetry distribution can be fitted by two half normal distributions with the most probable position deviating from the designed value. With the increase of parameter fluctuation degrees, the DCR-distribution asymmetry and deviation increase in nonlinear manners, implying the complexity and difficulty in simply predicting the performance fluctuations of SPADs. The mechanism is thought to be associated with the near-exponential dependence of DCR on the excess bias. This analysis is quite helpful to the design of focal plane SPAD arrays.