2.34 kV β-Ga2O3 vertical trench RESURF Schottky barrier diode with sub-micron fin width

In this letter, we present a kilovolt-class β-Ga2O3 vertical trench Schottky barrier diode with a field plate incorporating narrow fin width (Wfin) structures of sub-micron dimensions. We used a nanolaminate dielectric comprising a stack of multiple thin TiO2 and Al2O3 layers as RESURF dielectric and for field plate edge termination. Devices with both Wfin of 200 and 500 nm demonstrate excellent on-state performance with specific on-resistance (Ron,sp) of 9.4–12.37 mΩ-cm2 and 1010 rectification ratio. A self-aligned photoresist planarization and etch-back process was employed to expose the top of the fins for Schottky contact formation, eliminating critical lithographic alignment challenges in sub-micron scale processing. We achieved a breakdown of 2.34 kV with very low leakage currents before catastrophic breakdown. The measured breakdown voltage is limited by the dielectric breakdown as verified by the metal–oxide–semiconductor test structure. TCAD simulation shows a reduced electric field at the surface of the metal–semiconductor junction due to the RESURF effect, resulting in very low reverse leakage before breakdown. The parallel plane electric field in the β-Ga2O3 is extracted to be 3.4 MV/cm using the extracted drift layer doping profile from high voltage CV measurements. A power figure of merit of 0.85 GW/cm2 (0.58 GW/cm2 with current spreading) was calculated. Enhanced RESURF by integration of high-k dielectrics with self-aligned photoresist planarization offers a promising pathway toward high figure of merit, low leakage high-performance vertical devices.