Vacuum Annealed β-Ga₂O₃ Recess Channel MOSFETs With 8.56 kV Breakdown Voltage

This letter reports vacuum annealing of lateral field-platedβ-Ga2O3 MOSFETs with significant current recovery and improvement in the on-state resistance,Rₒₙ, 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) grownβ-Ga2O3 wafers to better understand the effects of vacuum annealing. We see a clear trend of vacuum annealed devices showing no reduction in breakdown voltages,Vbr, as compared to polymer passivated MOSFETs. This trend holds for identical gate-drain separation,Lgd, varying from20 ~μ mto60 ~μ m. Devices show up to 10 times reduction inRₒₙas compared to previously reportedRₒₙfor SU-8 passivated devices. For MBE sample,Vbrof 7.16 kV for aLgd=40 ~μ mdevice, with an average field strength of 1.79 MVcm^-1and peak drain current density of 40 mA/mm, is reported.Rₒₙis897 Ω. mm, giving Baliga’s Figure of Merit (BFOM) as 5.71 MWcm^-2. For aLgd=60 ~μ mdevice, we report record high breakdown of 8.56 kV with BFoM of 4.9 MWcm^-2. For MOCVD grown sample, aLgd=60 ~μ mdevice hasVbrof 6.11 kV,Rₒₙof 1.98kΩ. mm and corresponding BFoM of 1.88 MWcm^-2. Transfer Length Method (TLM) analysis indicates incomplete post etch current recovery after vacuum annealing.