Effects of microwave plasma treatment on β-Ga2O3 Schottky barrier diodes

Abstract In this work, the effects of O 2 or N 2 microwave plasma treatment on β -Ga 2 O 3 surface prior to Schottky metal deposition are reported. The device uniformity of Schottky barrier diodes is improved significantly by the microwave plasma treatments without any degradation such as ideality factor (near 1.0), and on-state resistance ( R on ∼3 mΩ cm 2 ). The standard deviation of Schottky barrier height (SBH, φ B ) is as small as less than 10 m eV. Kelvin probe force microscope analysis shows that the surface electrostatic potential after O 2 microwave plasma treatment is lower than that of the N 2 microwave plasma treatment, which is consistent with the change of SBH obtained by capacitance–voltage ( C – V ) and current–voltage ( I – V ) measurements. The relatively low SBH with O 2 microwave-plasma treatment corresponds to the high reverse leakage current. The oxygen related adsorption at metal/Ga 2 O 3 interface by O 2 microwave plasma treatment confirmed by x-ray photoelectron spectroscopy can be attributed to the SBH and surface potential lowing.