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.