Metal-Al 2 O 3 -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 (Ga 2 O x ) 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 Ga 2 O x interface layer which reduced trapped charge density ( Q ot ) and interface trap density ( D it ) of n-MOSCAPs. The thickness of the Ga 2 O 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 × 10 11 to 7.77 × 10 11 cm −2 eV −1 and the D it near the valence band edge decreased from 9.78 × 10 12 to 6.27 × 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.