Metal-Al<inf>2</inf>O<inf>3</inf>-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 (Ga2O x ) formed by ultraviolet/ozone (UV/O3) treatment. X-ray photoelectron spectroscopy, transmission electron microscopy, and X-ray dispersive spectroscopy were employed to investigate the Ga2O x interface layer which reduced trapped charge density (Q ot) and interface trap density (D it) of n-MOSCAPs. The thickness of the Ga2O x layer was found to be ∼1 nm. From the frequency-dispersion capacitance-voltage measurements, the Q ot averaged over the GaN bandgap decreased from 9.40 × 1011 to 7.77 × 1011 cm-2 eV-1 and the D it near the valence band edge decreased from 9.78 × 1012 to 6.27 × 1012 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. © 2020 The Japan Society of Applied Physics.