10 kV $β$-Ga$_2$O$_3$ Sub-Bandgap Triggered Impurity Photoconductive Semiconductor Switches (i-PCSSs): Lessons for Optimal Design

Imteaz Rahaman; Hunter Ellis; Afrouz Taherian; Seyedeh Shadi Mirmohammadi; Botong Li; Berardi Sensale Rodriguez; Michael A. Scarpulla; Kai Fu

arXiv · 2610.41049

10 kV $β$-Ga$_2$O$_3$ Sub-Bandgap Triggered Impurity Photoconductive Semiconductor Switches (i-PCSSs): Lessons for Optimal Design

Imteaz Rahaman·Hunter Ellis·Afrouz Taherian·Seyedeh Shadi Mirmohammadi·Botong Li·Berardi Sensale Rodriguez·Michael A. Scarpulla·Kai Fu

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Abstract

$β$-Ga$_2$O$_3$ photoconductive semiconductor switches (PCSSs) are attractive for high-voltage operation, but above-bandgap triggering requires deep-ultraviolet excitation. Here, we investigate a 650-um-thick, 0.01% Fe-doped $β$-Ga$_2$O$_3$ impurity PCSS with a 5-mm lateral gap under continuous-wave (CW) 808-nm sub-bandgap excitation at biases up to 10 kV ( 20 kV cm^-1). The device exhibited clear sub-bandgap photoconductive switching. As the optical power density increased from 0.64 to 3.18 W cm^-2, the ON-state current increased progressively while the ON-state resistance decreased, consistent with enhanced defect-assisted photocarrier generation. A higher applied bias further strengthened the switching response through enhanced field-assisted carrier transport. The ON/OFF ratio increases with optical power density but exhibits a nonmonotonic bias dependence, reaching approximately 15-16 near 5-7 kV. At 10 kV, increased OFF-state conduction and non-ideal transient behavior reduce the switching contrast. These results demonstrate near-infrared photoconductive switching but also highlight critical trade-offs in photoconductive thresholds for impurity states.

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Imteaz Rahaman, Hunter Ellis, Afrouz Taherian, Seyedeh Shadi Mirmohammadi, Botong Li, Berardi Sensale Rodriguez, Michael A. Scarpulla, Kai Fu. 2026-10-29. 10 kV $β$-Ga$_2$O$_3$ Sub-Bandgap Triggered Impurity Photoconductive Semiconductor Switches (i-PCSSs): Lessons for Optimal Design. https://arxiv.org/abs/2610.41049

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