Effect of annealing on GaN-insulator interfaces characterized by metal-insulator-semiconductor capacitors

GaN metal-oxide-semiconductor (MOS) capacitors have been used to characterize the effect of annealing temperature and ambient on GaN-insulator interface properties. Silicon dioxide was deposited on n-type GaN at 900 °C by low-pressure chemical vapor deposition and MOS capacitors were fabricated. The MOS capacitors were used to characterize the GaN-SiO₂ interface with a low interface-state density of 3 × 10¹¹ cm^-2eV^-1 at 0.25 eV below the conduction band edge, even after annealing in N₂ at temperatures up to 1100 °C; however, insulator properties were degraded by annealing in NO and NH₃ at 1100 °C.