Effects of postmetallization annealing on interface properties of Al2O3/GaN structures

In this study, we investigated the effects of postmetallization annealing (PMA) on the interface properties of GaN metal-oxide-semiconductor (MOS) structures using Al2O3 prepared by atomic layer deposition. Excellent capacitance-voltage (C-V) characteristics without frequency dispersion were observed in the MOS sample after PMA in N2 ambient at 300-400 °C. The PMA sample showed state densities of only at most 4 × 1010 cm−1 eV−1. A geometric phase analysis of transmission electron microscopy images after PMA revealed a uniform distribution of the lattice constant near the Al2O3/GaN interface, leading to the improved bond termination and bonding order configuration along the interface.