Capacitance Dependence of Carrier Transport in Nonlinear GaAs Photoconductive Semiconductor Switch at nJ Optical Excitation

Carrier transport is the fundamental factor determining the macroscopic transient characteristics of the gallium arsenide photoconductive semiconductor switch (GaAs PCSS), with pulse width as a visible manifestation. In this letter, the influence of capacitance on the transient characteristics of the GaAs PCSS is investigated at an optical excitation of 136nJ. The results indicate that the electrical pulse gradually transforms from a compressed pulse with high amplitude and narrow pulse width to a typical nonlinear lock-on waveform as the capacitance increases. Furthermore, the carrier transport dynamics and the evolution of high-field domains are analyzed through a two-dimensional device-circuit hybrid simulation. The change in carrier transport is regarded as the primary cause that regulates the output electric pulse width. The adjustability of the GaAs PCSS output electrical pulse provides the possibility of achieving a more optimal option for the different application requirements.