Vacuum annealed β-Ga2O3 recess channel MOSFETs with 8.56 kV Breakdown Voltage

This letter reports vacuum annealing of lateral field-plated β-Ga 2 O 3 MOSFETs with significant current recovery and improvement in the on-state resistance, R on , after Reactive Ion Etching (RIE) induced damage. We fabricate and characterize MOSFETs based on Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD) grown β-Ga 2 O 3 wafers to better understand the effects of vacuum annealing. We see a clear trend of vacuum annealed devices showing no reduction in breakdown voltages, V br , as compared to polymer passivated MOSFETs. This trend holds for identical gate-drain separation, L gd , varying from 20 μm to 60 μm. Devices show up to 10 times reduction in R on as compared to previously reported R on for SU-8 passivated devices. For MBE sample, V br of 7.16 kV for a L gd = 40 μm device, with an average field strength of 1.79 MVcm -1 and peak drain current density of 40 mA/mm, is reported. R on is 897 Ω∙mm, giving Baliga's Figure of Merit (BFOM) as 5.71 MWcm -2 . For a L gd = 60 μm device, we report record high breakdown of 8.56 kV with BFoM of 4.9 MWcm -2 . For MOCVD grown sample, a L gd = 60 μm device has V br of 6.11 kV, R on of 1.98 kΩ∙mm and corresponding BFoM of 1.88 MWcm -2 . Transfer Length Method (TLM) analysis indicates incomplete post etch current recovery after vacuum annealing.