Study on surface leakage current at sidewall in InP-based avalanche photodiodes with mesa structure

A multi-mesa InGaAs/InP avalanche photodiode (APD) with the advantage of the completely restricted electric field is proposed. The surface defects, which are the reasons for the sidewall leakage current generation in the mesa-structure APD, are theoretically studied, and then a sidewall leakage current model is developed. The Silvaco Atlas device simulation tool is used to analyze the generation mechanism of the sidewall leakage current, and the effects of different mesa structures on the sidewall leakage current of the APD are compared. The simulation results show that the sidewall leakage current of the multi-mesa APD is about zero and is not affected by the terrace size, which can be contributed by a very weak electric field at the sidewall.