Circuit model simulation for separate absorption, grading and multiplication avalance photodiodes (SAGM-APD) considering gradual changes of the electric field in active region

In this paper, we obtain a circuit model for separate absorption, grading and multiplication avalanche photodiodes (SAGM-APD). In this circuit modelling we consider the gradual changes of electric field in active region using split- step method . This circuit model is based on the carrier rate equations in the different regions of the device. Using the model we obtain the quantum efficiency and dark current. As examples, InP/InGaAsP/InGaAs SAGM-APD is simulated. There is a good agreement between the simulation and experimental results.