Enhancement-mode β-Ga2O3 U-shaped gate trench vertical MOSFET realized by oxygen annealing

Vertical metal-oxide-semiconductor field effect transistor (MOSFET) is essential to the future application of ultrawide bandgap beta-Ga2O3. In this work, we demonstrated an enhancement-mode beta-Ga2O3 U-shaped gate trench vertical metal-oxide-semiconductor field effect transistor (UMOSFET) featuring a current blocking layer (CBL). The CBL was realized by high-temperature annealing under oxygen ambient, which provided electrical isolation between the source and drain electrodes. The CBL thicknesses of different annealing temperatures were derived from C-V measurements and the Fermi level position of the sample surfaces of different annealing temperature was characterized by x-ray photoelectron spectroscopy measurements, indicating good process controllability. Furthermore, photoluminescence spectra were measured to study the effect of oxygen annealing. The fabricated UMOSFET showed normally off with a V-th of 11.5 V, an on-state resistance of 1.48 omega cm(2), a maximum on-state current of 11 A/cm(2), an on-off ratio of 6 x 10(4), and a three-terminal breakdown voltage over 100 V. This work paves a way to form a CBL and broadens the design space for high-power beta-Ga2O3 vertical transistors. Published under an exclusive license by AIP Publishing.