Recessed-Gate Enhancement-Mode $\beta $ -Ga2O3 MOSFETs

We report enhancement-mode
$\beta $
-Ga
₂
O
₃
(BGO) MOSFETs on a Si-doped homoepitaxial channel grown by molecular beam epitaxy. A gate recess process is used to partially remove the epitaxial channel under the 1-
$\mu \text{m}$
gated region to fully deplete at
${V}_{\textsf {GS}}= 0$
V. BGO MOSFETs achieve drain current density near 40 mA/mm and
${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$
ratio ~10
⁹
which is the highest reported for homoepitaxial normally-off BGO transistors. At
${V}_{\textsf {GS}}= \textsf {0}$
V, a breakdown voltage of 198 and 505 V is achieved with the source–drain spacing of 3 and
$8~\mu \text{m}$
, respectively. The power switching figure of merits for dc conduction and dynamic switch losses meet or exceed the theoretical silicon limit and previously reported depletion-mode BGO transistors.