Optimization and modeling of avalanche photodiode structures: Application to a new class of superlattice photodetectors, the p-i-n, p-n homojunction, and p-n heterojunction APD´s

The development of predictive and diagnostic models for high-field, high-energy devices, i.e., avalanche photodiodes and IMPATT diodes, requires a first principles determination of the impact ionization rates in both bulk semiconductor material and in device structures. We have developed such a model using a combined numerical determination of the ionization rates from an ensemble Monte Carlo calculation. In conjunction with recently derived expressions for the gain, excess noise factor, and bandwidth, these relevant engineering figures of merit can be assessed in various new superlattice device Structures. Specifically, we present optimal designs of three new superlattice APD´s, the p-i-n, p-n homojunction, and p-n heterojunction devices, for both lightwave communications and digital applications using the general device model described herein.