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

TL;DR

This study demonstrates that sub-bandgap excitation at 272 nm significantly enhances carrier transport and device performance in Fe-doped Ga2O3-based optoelectronic switches, achieving record photocurrent and low resistance through optimized device design.

Contribution

It reveals the critical role of sub-bandgap illumination in activating deep defect states, leading to high-performance Ga2O3 switches with optimized geometry and excitation spectrum.

Findings

Record photocurrent of 4.14 A achieved

Lowest on-resistance of 10.4 Ω recorded

High responsivity-conductance FoM of 4.7×10⁻⁶ S/W

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 $\beta$-Ga$_2$O$3$. By systematically varying the anode grid pitch ($20-80\ \mu\text{m}$) 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 $40\ \mu\text{m}$ anode pitch, the fabricated device achieves a high peak photocurrent of $4.14\ \text{A}$ and a record-low on-resistance of $10.4\ \Omega$. 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 $\beta$-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.