ABSTRACT
We have studied Impact ionization in MSM optical detectors and MESFET’s using a self-consistent Monte Carlo method. The model showed that in both devices impact ionization set in earlier than would be expected from a naive interpretation of the applied potential. In the case of MSM photodetectors, current multiplication was found to increase with incident light intensity - this being due to screening effects within the device. In the case of MESFET’s ionization and early breakdown of the device was found to be caused by the onset of wandering accumulation layers. The qualitative behaviour of both devices predicted by the model is confirmed by experimental observations.
