214 MW/cm2 vertical β-Ga2O3 UMOSFETs enabled by HF sidewall treatment

Vertical β-Ga2O3 UMOSFETs incorporating current-blocking layers (CBLs) typically suffer from increased on-resistance, primarily caused by deep-level defect states in the trench sidewalls that trap free electrons. In this work, a hydrofluoric acid (HF) solution sidewall treatment was introduced prior to gate dielectric deposition to modify the trench surface. This process enables the effective incorporation of fluorine atoms into the sidewall region, which reduces the interface trap density and improves carrier transport characteristics. The fabricated vertical β-Ga2O3 UMOSFETs achieved a specific on-resistance of 6.0 mΩ·cm2, a channel mobility of 19.1 cm2/V·s, and a breakdown voltage of 1132 V. These results demonstrate that HF sidewall treatment provides a simple and efficient surface engineering approach for significantly enhancing the conduction performance and overall electrical characteristics of β-Ga2O3 UMOSFETs.