Surface Modification of GaN Substrate by Atmospheric Pressure Microplasma

Abstract

In this study, surface modification of GaN substrates by microplasma was investigated. Microplasma, which is an atmospheric pressure nonthermal plasma and a type of dielectric barrier discharge, was generated with a pair of electrodes that were covered with a dielectric layer and that faced each other at a small discharge gap under 100 µm with a spacer. Owing to small discharge gaps (0–100 µm) and to the assumed specific dielectric constant of εr = 104, a high-intensity electric field (107–108 V/m) could be obtained with a relatively low discharge voltage of only about 1 kV at atmospheric pressure. The GaN surface was treated with atmospheric pressure microplasma using Ar and N2 as process gases and powered by AC and pulse power supplies. Modifications of the surfaces were observed after the treatment and they depend on the gas process, treatment time, and power supply. The surface was analyzed before and after the treatment by X-ray photoelectron spectroscopy (XPS) analysis and Field-emission scanning electron microscopy (FE-SEM).