Design and process simulation of p-well guard ring Si Avalanche Photodiode

The design, simulation and characterization of Silicon Avalanche Photodiode (SAPD) that can be implemented with SILVACO TCAD tool are presented. This SAPD design used the diffusion of p-wells to create a low p layer doping density as the guard ring to prevent the premature breakdown at the edge of the device. The result demonstrated that the proper gap length between p-wells to create the guard ring allows SAPD to work in the Geiger mode. This showed that by developing a low-doped guard ring at the edge of the junction, it will reduce the electric field, minimize the avalanche current and the edge breakdown can be prevented. In this paper, the SAPD with square shape active area of 2 × 2 μm² and low doped p-well guard ring has V_BD of 27 V and avalanche current of 0.85 pA.