Optimum design of the charge layer for avalanche photodiodes

InGaAs/InP avalanche photodiodes (APDs) are widely used for high-speed optical receivers in optical fiber communication systems. In this paper, the model for separate absorption grading charge multiplication (SAGCM) InGaAs/InP APDs has been performed based on the device simulator Silvaco ATLAS. Moreover, the test structure was fabricated and the measured current-voltage characteristics were compared with the simulated data to verify the model. The SRH current, TAT current, BBT current and avalanche amplification combined together as dark current has been extracted by simulation, meanwhile the further numerical analysis of charge sheet density variation on the dark current components has been given. In addition, we also proposed the optimized charge sheet density range for different multiplication layer, which may be helpful for the optimum design of SAGCM APDs.