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 (SBDs) is improved significantly by the microwave plasma treatments without any degradation such as ideality factor (near 1.0), and on-state resistance (Ron ~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 (KFM) 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) andCurrent-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/Ga2O3interface by O2microwave plasma treatment confirmed by X-ray photoelectron spectroscopy (XPS) can be attributed to the SBH and surface potential lowing.

A Review of β-Ga2O3 Power Diodes

“…The Bardeen model suggests that electron transfer from the semiconductor to the metal is mediated by interface states on the contact surface, assuming a continuous distribution of surface states defined by a neutral energy level Φ 0 , with the Fermi level position determined by the location of the surface states within the bandgap, which is the Fermi level pinning effect [115]. Therefore, the surface states of β-Ga 2 O 3 also significantly affect device performance; experiments have found that treatments such as oxygen plasma and annealing, as well as chemical solution cleaning, can effectively reduce the density of surface states on β-Ga 2 O 3 , enhancing device performance, while etching and plasma bombardment may increase surface state density, leading to poorer device performance [116][117][118][119][120][121].…”

Flexible gallium oxide electronics

“…Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Ga 2 O 3 has an exceptionally high Baliga figure of merit of 3214.1, making it a promising candidate for various applications, including power electronics, solar-blind ultraviolet (UV) detectors, memory devices, and electronics that operate under harsh environments such as high temperature and radiation [11][12][13][14][15][16][17][18].…”