[11¯00]∕(1102)twin boundaries in wurtziteZnOand group-III-nitrides

The atomic structure and electronic effects of the $\left[1\overline{1}00\right]∕\left(1102\right)$ twin boundary in $\mathrm{ZnO}$ are studied using the combination of high-resolution $Z$-contrast imaging, first-principles density-functional total-energy calculations, and image simulations. The twin boundary is found to have the head-to-tail polarity configuration, which avoids dangling bonds, leading to a low twin-boundary energy of $0.040\mathrm{J}∕{\mathrm{m}}^2$. We further find that the same twin boundaries in wurtzite group-III-nitrides adopt the same structure, but the twin-boundary energies, $0.109\mathrm{J}∕{\mathrm{m}}^2$ in $\mathrm{AlN}$, $0.107\mathrm{J}∕{\mathrm{m}}^2$ in $\mathrm{GaN}$, and $0.051\mathrm{J}∕{\mathrm{m}}^2$ in $\mathrm{InN}$, are higher than in $\mathrm{ZnO}$. Investigations of the electronic structure reveal that the twin boundary does not introduce localized energy states in the band gap in either $\mathrm{ZnO}$ or the wurtzite group-III-nitrides.