Study on impact ionization in charge layer and multiplication layer of InAlAs/InGaAs SAGCM avalanche photodiodes

Impact ionization in charge layer and multiplication layer of InAlAs/InGaAs avalanche photodiodes (APDs) with separated absorption, grading, charge and multiplication structures has been studied by two-dimensional simulations using Silvaco TCAD. Special attention has been paid to the charge layer and multiplication layer with different thicknesses and doping concentrations in order to optimize the structure for low band discontinuities and an appropriate electric field distribution. Band-edge profile calculations as well as current-voltage characteristic and electric field results of the APDs will be discussed in this article.