Reconstructed structures of the GaN and ZnO(10$\overline{1}$1) anion semipolar surfaces were studied using density functional theory calculations. The twofold-coordinated anion atoms on the unreconstructed surfaces form anion dimers with reduced surface hole density. The residual holes on the dimerized surfaces are additionally compensated by formation of a dimer vacancy (DV) in every four $2\times 1$ cells on GaN($10\overline{1}1$) and in two $2\times 1$ cells on ZnO($10\overline{1}1$). The electrostatically stable $4\times 2$ DV reconstruction on the GaN($10\overline{1}1$) surface is found to be more stable than the previously suggested structures, and the $2\times 2$ DV reconstruction on the ZnO($10\overline{1}1$) surface explains the transmission electron microscopy observations.

• Received 12 July 2011

DOI:https://doi.org/10.1103/PhysRevB.84.115318