Ga2O3 MOSFET Device with Al2O3 Gate Dielectric

n-typed beta-Ga2O3 was homoepitaxially grown by metal organic chemical vapor deposition (MOCVD) on a Fe-doped semi-insulating (010) Ga2O3 substrate. The structure consisted of a 600 nm undoped (UID) Ga2O3 buffer layer and 200 nm Si-doped channel layer. High-temperature Ohmic alloy experiments were taken on two kinds of n-typed beta-Ga2O3 with Si donor concentrations of 3.0 x 10(17) and 1.0 x 10(18) cm(-3). It's hard to realize good Ohmic contact on the beta-Ga2O3 epitaxial layer with donor concentrations of 3.0 x 10(17) cm(-3). The lowest Ohmic value of 9.8 Omega.mm was obtained on the substrate with donor concentrations of 1.0 x 10(18) cm(-3). Metal-oxide-semiconductor field-effect transistor (MOSFET) was fabricated based on homoepitaxial beta-Ga2O3 film with donor concentrations of 1.0x 10(18) cm(-3), in which Al2O3 grown by atomic layer deposition (ALD) was used as gate dielectric. The drain saturation current of the fabricated device reached 108 mA/mm at V-gs of 2 V, and a high peak transconductance of 17 mS/mm was obtained. Due to poor gate leakage, the three-terminal off-state breakdown voltage was just 23 V at V-gs = -12 V The breakdown characteristics can be improved by introducing HfO2 with high dielectric constant or Al2O3/HfO2 composite structure.