Theory of the temporal response of a simple multiquantum-well avalanche photodiode

Numerical and analytically based calculations of the impulse response function of a simple GaAs-AlGaAs multiquantum-well avalanche photodiode are presented. The numerical approach involves the direct simulation of the electron and hole transport in the device. An iterative approach is used in that the parent electron distribution is first simulated yielding the velocity profile as a function of position, transmit-time distribution of the parent and daughter electrons, and the daughter-hole distribution. The daughter-hole distribution is subsequently simulated using the time of birth and spatial location of each secondary hole as initial conditions. The calculation continues iteratively in this fashion yielding a picture of the time evolution of the impulse response function. Both analytical and simulation results are presented for single-carrier -initiated single-carrier-multiplication (SCISCM) devices. The similarities and differences in the outcomes of the two approaches are instructive, Simulation results are presented only for devices in which secondary hole-initiated ionization occurs.>