Record Responsivity-conductance Performance in Sub-bandgap-triggered Ga2O3 PCSS

Abstract

We present an investigation into the role of anode grid pitch and excitation spectrum on the performance of high-power optoelectronic switches utilizing Fe-doped ${\hat{I}}^2$-Ga${}_2$O$3$. By systematically varying the anode grid pitch ($20-80\hat{I}¼\text{m}$) and the excitation spectrum ($235-500\text{nm}$), we identify a crucial sub-bandgap regime, centered at $272\text{nm}$, that effectively activates deep-level defect states. This activation is shown to enable highly efficient bulk carrier transport, a significant contrast to conventional above-bandgap excitation which is hampered by shallow surface absorption. The sub-bandgap illumination promotes strong photocurrent generation and substantially improved carrier collection efficiency. Under optimized conditions, specifically utilizing a $40\hat{I}¼\text{m}$ anode pitch, the fabricated device achieves a high peak photocurrent of $4.14\text{A}$ and a record-low on-resistance of $10.4\hat{I}\text{c◯}$. To quantify this simultaneous high-performance achievement, we introduce a responsivity-conductance figure of merit ($\text{FoM}{}_{RC}$), which attains a record value of $4.7\times 10^{-6}\text{S/W}$. These findings robustly demonstrate the superior suitability of Fe-doped ${\hat{I}}^2$-Ga${}_2$O${}_3$ for next-generation high-power optoelectronic switching applications, enabling reliable ampere-level photocurrents coupled with minimized on-resistance through strategic device geometry optimization and sub-bandgap excitation.

6 pages, 6 figures