Atomic structure and relaxation behavior at AlN (0001)/Al2O3(0001) interface

The atomic structure of AlN (0001)/Al2O3(0001) interface, which is a model of a large lattice-mismatched film/substrate interface, was investigated by using static lattice calculations. Detailed analysis of the calculated structure revealed that the atomic relaxation behavior strongly depends on local atomic configurations of the interface. Interface distance became larger when Al atoms of AlN side and O atoms of Al2O3 side at the interface are in on-top configurations, while it became smaller when they are not in on-top configurations. The calculated structure qualitatively reproduced the experimental high-resolution transmission electron microscopy (HRTEM) image, which was obtained in our previous study. Such varieties of the atomic relaxation can be concluded to play one of the important roles for the formation of stable hetero-interface structures.