Impact Ionization in Absorption, Grading, Charge, and Multiplication Layers of InP/InGaAs SAGCM APDs With a Thick Charge Layer

We present a general methodology for device-level simulation of multiplication, noise, and receiver sensitivity in separate absorption, grading, charge, and multiplication avalanche photodiodes (SAGCM APDs) with a thick charge layer. According to the best of our knowledge, it is the first time to report the experimental evidence for impact ionization in combination of absorption, grading, charge layer with multiplication layers for SAGCM APDs. A thick charge layer was adopted in our InP/InGaAs APDs, which provides us a chance to elucidate the contribution of the electric field in the charge layer to the overall performance for SAGCM APDs. In addition, thereby performance dependence of SAGCM APDs on the thickness of charge layer has also been discussed. An empirical formula is proposed to predict the thickness of the InP multiplication layer of APDs with different charge doping levels for optimization in noise performance. The technological significance of the device-level simulation on the design and development of SAGCM APDs has also been addressed.