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

Abstract

In this work, the effects of O2 or N2 microwave plasma treatment on β-Ga2O3 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 cm2). The standard deviation of Schottky barrier height (SBH, φB) is as small as less than 10 m eV. Kelvin probe force microscope analysis shows that the surface electrostatic potential after O2 microwave plasma treatment is lower than that of the N2 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 O2 microwave-plasma treatment corresponds to the high reverse leakage current. The oxygen related adsorption at metal/Ga2O3 interface by O2 microwave plasma treatment confirmed by x-ray photoelectron spectroscopy can be attributed to the SBH and surface potential lowing.