InGaAs/InAlAs SAGCMCT avalanche photodiode with high linearity and wide dynamic range

Abstract

Linearity is a very important parameter to measure the performance of avalanche photodiodes (APDs) under high input optical power. In this paper, the influence of the absorption layer on the linearity of APDs is carefully studied by using bandgap engineering with the structure model of separated absorption, grading, charge, multiplication, charge, and transit (SAGCMCT). The simulated results show that in the hybrid absorption layer device structure the 1 dB compression point can be improved from -9 dBm to -2.1 dBm by increasing the proportion of the p-type absorption layer. In the device structure with only one absorption layer, increasing the doping level of the absorption layer can also improve the 1 dB compression point from -8.6 dBm to 1.43 dBm at a gain of 10. Therefore, the absorption layer is very critical for the linearity of APDs.