Depletion and enhancement mode β-Ga2O3 MOSFETs with ALD SiO2 gate and near 400 V breakdown voltage

As a next generation wide bandgap semiconductor for power electronics, β-Ga
₂
O
₃
(Ga
₂
O
₃
) has shown a lot of potential in recent studies. It has been reported to have high Baliga's Figure of Merit (BFoM), a figure of merit for power devices, next only to diamond among wide bandgap semiconductor materials [1]. Moreover, a mature growth technology for large area substrates is a major practical advantage for cost effectiveness and rapid adaptation by industry [2]. Because of the advantages of this material, depletion mode MOSFETs and Schottky diodes based on Ga
₂
O
₃
with high breakdown voltages have been recently demonstrated [3][4]. However, enhancement mode MOSFETs are preferred in power electronics applications. All the previous work incorporated ALD Al
₂
O
₃
as gate barrier due to its high dielectric constant. However, a recent study reported that SiO
₂
/Ga
₂
O
₃
interface has a much bigger conduction band offset than that of Al
₂
O
₃
/Ga
₂
O
₃
[5] which is preferred in MOSFET. In addition, SiO
₂
/Ga
₂
O
₃
interface has a relatively low interface states density according to our recent data. These properties make SiO
₂
an attractive gate dielectric for Ga
₂
O
₃
power MOSFETs. Here, we first report depletion mode MOSFET on MBE grown Ga
₂
O
₃
with an ALD SiO
₂
gate. We also report the first successful enhancement mode MOSFET on β-Ga
₂
O
₃
. Both depletion mode and enhancement mode MOSFETs show near 400 V off state drain source breakdown voltage.