Metal-Al2O3-GaN capacitors with an ultraviolet/ozone plasma-treated interface

Abstract

In this study, interface quality of p-type GaN metal-oxide-semiconductor capacitors (n-MOSCAPs) improved with the interface oxide layer (Ga2Ox) formed by ultraviolet/ozone (UV/O-3) treatment. X-ray photoelectron spectroscopy, transmission electron microscopy, and X-ray dispersive spectroscopy were employed to investigate the Ga2Ox interface layer which reduced trapped charge density (Q(ot)) and interface trap density (D-it) of n-MOSCAPs. The thickness of the Ga2Ox layer was found to be similar to 1 nm. From the frequency-dispersion capacitance-voltage measurements, the Q(ot) averaged over the GaN bandgap decreased from 9.40 x 10(11) to 7.77 x 10(11) cm(-2) eV(-1) and the D-it near the valence band edge decreased from 9.78 x 10(12) to 6.27 x 10(12) cm(-2) eV(-1). The method to improve the interface quality could be applied to enhancement in the performance of p-GaN electronic devices such as MOS field-effect transistors and high-electron mobility transistors.