Monte Carlo simulation of impact ionisation in photodetectors

The authors have studied impact ionisation in optical detectors using a self-consistent Monte Carlo method. Current multiplication was found to be sensitive to both the applied potential and the incident light intensity. The amount of current multiplication was significantly higher than might be expected from a naive interpretation of the nominally applied field and this was attributed to screening effects within the device. The potential within the device was also significantly affected by the impact ionisation process and this in turn gave rise to an interesting structure (oscillations) in the current at higher incident light intensities and potentials