Vacuum Annealed β -Ga 2 O 3 Recess Channel MOSFETs With 8.56 kV Breakdown Voltage.

This letter reports vacuum annealing of lateral field-plated $\beta $ -Ga2O3 MOSFETs with significant current recovery and improvement in the on-state resistance, $\text{R}_{\text {on}}$ , 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 $\beta $ -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, $\text{V}_{\text {br}}$ , as compared to polymer passivated MOSFETs. This trend holds for identical gate-drain separation, $\text{L}_{\text {gd}}$ , varying from $20 ~\mu \text{m}$ to $60 ~\mu \text{m}$. Devices show up to 10 times reduction in $\text{R}_{\text {on}}$ as compared to previously reported $\text{R}_{\text {on}}$ for SU-8 passivated devices. For MBE sample, $\text{V}_{\text {br}}$ of 7.16 kV for a $\text{L}_{\text {gd}}$ = $40 ~\mu \text{m}$ device, with an average field strength of 1.79 MVcm $^{{-{1}}}$ and peak drain current density of 40 mA/mm, is reported. $\text{R}_{\text {on}}$ is $897 \Omega $. mm, giving Baliga’s Figure of Merit (BFOM) as 5.71 MWcm $^{{-{2}}}$. For a $\text{L}_{\text {gd}}$ = $60 ~\mu \text{m}$ device, we report record high breakdown of 8.56 kV with BFoM of 4.9 MWcm $^{{-{2}}}$. For MOCVD grown sample, a $\text{L}_{\text {gd}}$ = $60 ~\mu \text{m}$ device has $\text{V}_{\text {br}}$ of 6.11 kV, $\text{R}_{\text {on}}$ of 1.98 $\text{k}\Omega $. mm and corresponding BFoM of 1.88 MWcm $^{{-{2}}}$. Transfer Length Method (TLM) analysis indicates incomplete post etch current recovery after vacuum annealing. [ABSTRACT FROM AUTHOR]