a-SnO x /β-Ga 2 O 3 Junction Field-effect Phototransistor with High Responsivity and Fast Response Speed

Gallium Gallium oxide $\left(\mathrm{Ga}_{2} \mathrm{O}_{3}\right)$ is known for its exceptional properties, making it an ideal material for solarblind photodetectors. This study demonstrates a highperformance solar-blind UV phototransistor based on amorphous (a-) $\mathrm{SnO}_{\mathrm{x}}(1\lt \mathrm{x}\lt 2) / \beta-\mathrm{Ga}_{2} \mathrm{O}_{3}$ nanosheet heterojunction field-effect transistor. It exhibits excellent optoelectronic properties under 254 nm illumination, with ultra-high responsivity ($1.16 \times 10^{4} \mathrm{~A} / \mathrm{W}$) at weak light intensity. With increasing UV illumination, the device demonstrates an ultrafast response, achieving rise times as low as $487 \mu \mathrm{~s}$. The excellent performance originates from the strong interfacial built-in field enabling efficient carrier separation and suppressed recombination, photogating from trapped charges in $\mathrm{SnO}_{\mathrm{x}}$, and transistor transconductance amplification. The device provides a promising approach for solar-blind photodetection.