1230 V β-Ga2O3 trench Schottky barrier diodes with an ultra-low leakage current of <1 μA/cm2

Abstract

β-Ga2O3 vertical trench Schottky barrier diodes (SBDs) are realized, demonstrating superior reverse blocking characteristics than the co-fabricated regular SBDs. Taking advantage of the reduced surface field effect offered by the trench metal-insulator-semiconductor structure, the reverse leakage current in the trench SBDs is significantly suppressed. The devices have a higher breakdown voltage of 1232 V without optimized field management techniques, while having a specific on-resistance (Ron,sp) of 15 mΩ cm2. An ultra-low leakage current density of <1 μA/cm2 is achieved before breakdown, the lowest among all reported Ga2O3 Schottky barrier diodes. Fast electron trapping and slow de-trapping near the Al2O3/Ga2O3 interface are observed by repeated C-V measurements, which show an interface state ledge and positive shifts of flat-band voltages with increasing voltage stress. By comparison between pulsed and DC measurements, the device self-heating effect and the trapping effect are uncoupled. It is found that the trapping effect at the trench sidewall affects the on-resistance of the trench SBDs, even under pulsed conditions. With reduced trapping effect and better field management technique, the trench SBDs could further harvest the promising material properties of β-Ga2O3.