Schottky barrier height of boride-based rectifying contacts to p-GaN

Schottky contact formation on p-GaN using a W2B-based metallization scheme was investigated using x-ray photoelectron spectroscopy (XPS), current-voltage (I-V), and capacitance-voltage (C-V) measurements. The Schottky barrier height (SBH) determined from XPS is 2.7eV, whereas fitting of the I-V’s gives 1.2 and 3.8eV depending on the assumed mechanism of forward current flow. While the C-V’s and the measurement temperature dependence of the I-V’s support tunneling as being the dominant transport mechanism, this latter approach overestimates the true SBH of W2B∕p-GaN contacts due to the presence of an interfacial layer acting as an additional barrier to carrier transport.