Abstract

We present calculations of the temporal response of a doped quantum well avalanche photodiode made from the GaAs/AlGaAs material system. The calculations are based on both an ensemble Monte Carlo method and an analytic formulation based on the direct calculation of the impulse response function in terms of the density functions for the transit times. These analyses are applied to a doped quantum well structure in which single-carrier-initiated double-carrier multiplication conditions occur. The results show that the envelope of the impulse response function decays rapidly due to the negligible hole impact ionization rate, resulting in large-bandwidth operation of the device. The standard deviation of the impulse response function which results from both randomness in the gain and in the birth times is also presented. Based on these calculations, it is found that in APDs in which the hole ionization probability is small but not identically zero, that the bandwidth can still be characterized by the simple analytical expression, B = 1/2π [1/m(τ_e + τ_h)], where m is the number of stages present in the device and τ_e and τ_h are the electron and hole transit times in each stage, respectively.

© 1988 Optical Society of America