Transient Simulations and Modelling of Semi-Insulating GaAs Photoconductive Switches

The primary objective of this thesis is to develop a one-dimensional transient simulator for Photoconductive Semiconductor Switches (PCSS) taking into consideration the material characteristics, the internal physical effects, and the external circuit. Simulations have been performed to study the device behavior at different voltage levels for copper-doped silicon-compensated GaAs material, though other materials could easily be simulated by changing the parameters. The model includes hole transport, and the results demonstrate the effect of hole injection, with and without recombination centers. In addition to developing a one-dimensional transient simulator, the role of various physical effects, such as the field-dependence of trapping rates, field-dependent impact-ionization, and movement of internal domains, have also been analyzed. The thesis also suggests various other factors which could be included to make the device model more accurate. These include tailoring the impurity profiles to prevent lock-on, more accurate modelling of the contacts, spatial profiling of the excitation pulse and including impact-ionization for breakdown analysis. Finally discussions on possible expansion to a two-dimensional model and the potential for developing effective circuit models are presented.