Low-temperature preparation of GaN-SiO2 interfaces with low defect density. II. Remote plasma-assisted oxidation of GaN and nitrogen incorporation

Low-temperature remote plasma-assisted oxidation and nitridation processes for interface formation and passivation have been extended from Si and SiC to GaN. The initial oxidation kinetics and chemical composition of thin interfacial oxide were determined from analysis of on-line Auger electron spectroscopy features associated with Ga, N, and O. The plasma-assisted oxidation process is self-limiting with power-law kinetics similar to those for the plasma-assisted oxidation of Si and SiC. Oxidation using O2∕He plasma forms nearly pure GaOx, and oxidation using 1% N2O in N2 forms GaOxNy with small nitrogen content, ∼4–7at.%. The interface and dielectric layer quality was investigated using fabricated GaN metal-oxide-semiconductor capacitors. The lowest density of interface states was achieved with a two-step plasma-assisted oxidation and nitridation process before SiO2 deposition.