An improved composite JTE technique with increased tolerance to interface charges for 2.8 kV β -Ga2O3 Schottky rectifier

This paper presents an efficient high-k BaTiO3 dielectric assisted junction termination extension (BTO-JTE) technique for vertical β-Ga2O3 Schottky barrier diodes (SBDs), to reduce the sensitivity of breakdown voltage (BV) to interface charges. In comparison with single-zone JTE (SZ-JTE), the BTO-JTE creates a more uniform electric field distribution with significantly reduced peak electric field at the edges of the Schottky junction or JTE. As a result, a highest BV of 3 kV and a low specific on-resistance (Ron,sp) of 6.2 mΩ cm2 were achieved, yielding a highest power figure-of-merit (PFOM) of 1.45 GW/cm2. Importantly, compared to the SZ-JTE SBDs, BTO-JTE SBDs exhibit significantly better BV uniformity across the entire wafer and an average BV of 2.81 kV with a smaller standard deviation of 0.1 kV. Combined with an average Ron,sp of 6.9 mΩ cm2, an average PFOM of 1.14 GW/cm2 is achieved, which still ranks among the best reported values for vertical β-Ga2O3 SBDs. Based on experimental and simulation results, it was validated that high-k BaTiO3 dielectric can suppress the negative impact of interface charges on the efficiency of BTO-JTE. This work presents a valuable strategy to improve the electric field management efficiency of JTE structures in the presence of interface charge, enabling robust kilovolt-class β-Ga2O3 power devices.