Performance Improvement of a β-Ga₂O₃-Based Solar-Blind Metal Oxide Semiconductor Field-Effect Phototransistor Using In Situ Ozone Pretreatment Technology

In this work, we demonstrated a high-performance $\beta $ -Ga₂O₃ solar-blind metal oxide semiconductor field-effect phototransistor (SBPT) with low-temperature in situ ozone (O₃) pretreatment technology. The Ga-O bonding quality and oxygen content of the $\beta $ -Ga₂O₃ surface before and after O₃ pretreatment were first determined by X-ray photoelectron spectroscopy (XPS). The percentage of substable O to total O decreased from 8.6% to 2.7% after the in situ O₃ pretreatment, and the peaks of substable Ga-O bonds moved closer to those of stable Ga-O bonds, indicating an improvement in the Ga-O bonding quality. Compared with SBPT without O₃ pretreatment, devices with O₃ pretreatment exhibited excellent photoelectrical properties, including a large photo-to-dark current ratio (PDCR) of $1.4\times10$ ⁷, a high UV-C/UV-A rejection ratio ( ${R}_{254 \,\,\text{nm}}/{R}_{365 \,\,\text{nm}}$ ) of $2.1\times10$ ⁷, a high responsivity ( ${R}$ ) of $4.37\times10$ ⁶ A/W, a large quantum efficiency (EQE) of $2.2\times10$ ⁷%, and a high detectivity ( ${D}^{\ast }$ ) of $2.8\times10$ ¹⁸ Jones. The rise time ( $\tau _{r}$ ) and decay time ( $\tau _{d}$ ) are extracted to be 70 and 23 ms after O₃ pretreatment. The optimized parameters of the device illustrate that low-temperature in situ O₃ pretreatment technology is a simple but effective approach to improve the performance of $\beta $ -Ga₂O₃-based SBPT.