Investigation of initial growth process of GaN film on sapphire using computational chemistry

We have performed molecular dynamics (MD) simulations and periodic density functional calculations to investigate the interatomic interactions of the GaN/sapphire (0001) interface and the energetically stable site of GaN molecule on the sapphire (0001) surface. The MD simulations indicate that the mobility of the Ga atoms is larger than that of the N atoms on the sapphire (0001) surface, as the Al-N interaction is stronger than the O-Ga interaction. The density functional calculations also suggest that the formation of the Al-N bond is most energetically stable on the sapphire (0001) surface. Since the sapphire (0001) substrate is terminated with Al atoms in the reductive atmosphere, we assumed that the formation of Al-N bonds is dominant at the GaN/sapphire (0001) interface.