Simulation of SAGCM structure InGaAs/InP SPAD using COMSOL multiphysics

InGaAs/InP single photon avalanche photodiode (SPAD) is important for quantum communication, and LIDAR applications in the near-infrared (NIR) wavelength range, between 0.9 µm and 1.7 µm. Compared with other optoelectronic devices, SPAD has two main advantages: high quantum efficiency and high detection efficiency. In this study, the design and simulating of a separate absorption, grading, charge, and multiplication (SAGCM) structure InGaAs/InP SPAD were conducted by using COMSOL Multiphysics. The electric-field distribution was studied under the given thickness and dopant concentration of each layer of the SPAD. It was found that the edge pre-breakdown of planar-type SPAD resulted from the intense electric field at the junction bend can be prevent from happening by using gaussian type dopant distribution profile. The punch-through voltage and the breakdown voltage were also focused. The results show that the punch-through voltage and the breakdown voltage was 55 V and 65V respectively. In addition, the electric field nonuniformity of the avalanche area increases greatly after the bias voltage exceeded the punch-through voltage.