Density functional theoretical study of surface structure and adatom kinetics for wurtzite AlN

Abstract

Density-functional calculations concerning the structure and stability of wurtzite AlN surfaces are presented. Specifically, (0001) and $\left(000\overline{1}\right)$ polar surfaces and $\left(1\overline{1}00\right)$ and $\left(11\overline{2}0\right)$ nonpolar surfaces are discussed in detail. Binding energies, migration pathways, and diffusion barriers for relevant adatoms such as Al, Ga, and N on these polar and nonpolar surfaces are determined. The calculation indicates low diffusion barrier for Al adatom on Al terminated (0001) surface, whereas the N adatom seems to have lower diffusion barrier on N terminated $\left(000\overline{1}\right)$ surfaces. A strong anisotropy was observed for diffusion behavior for Al adatom on $\left(1\overline{1}00\right)$ and $\left(11\overline{2}0\right)$ surfaces in the $\left[11\overline{2}0\right]$ and [0001] directions, respectively.