Investigation on Avalanche and Optoelectronic Response in Ga2O3 Photoconductive Semiconductor Switches

Photoconductive semiconductor switches (PCSSs) are noted for the rapid turn-on time and optically isolated triggering, making them suitable for high-power applications. Gallium oxide (Ga₂O₃), as an ultra-wide bandgap semiconductor, is promising for use in PCSSs with ultrahigh breakdown voltage and power density. This study investigates the avalanche process of Ga₂O₃ PCSSs triggered by pulsed optical sources through computational simulations, focusing on the electric field distribution, carrier dynamics, and optoelectronic response. The responsivity of Ga₂O₃ PCSS exceeds 100 mA/W when the optical power ranges from $10^{4}$ to $10^{6}$ W/cm². The rise time of the switch significantly decreases from 6.5 to 2 ns with an electric field of 6 MV/cm. Results reveal that a high-density avalanche domain forms and propagates within the device with peak electric fields ranging from 6 to 8 MV/cm. Furthermore, we demonstrate that the switching time of Ga₂O₃ PCSS can be shorter than 500 ps. This research provides design guidance and crucial insights into the carrier dynamics of an ultrafast Ga₂O₃ PCSS.