The homoepitaxial growth of $m$-plane $(1\overline{1}00)$ GaN was investigated by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions. The surface morphologies as a function of sample miscut were studied, providing evidence for a strong growth anisotropy that is a consequence of the anisotropy of Ga adatom diffusion barriers on the $m$-plane surface recently calculated ab initio [Lymperakis and Neugebauer, Phys. Rev. B 79, 241308(R) (2009)]. We found that substrate miscut toward $[000\overline{1}]$ implies a step flow toward $\langle 11\overline{2}\overline{6}\rangle$ while substrate miscut toward $[0001]$ causes formation of atomic steps either perpendicular or parallel to the $[0001]$ direction, under N-rich conditions at 730 ${}^{°}$C. We describe the growth conditions for achieving atomically flat $m$-plane GaN layers with parallel atomic steps.

• Received 23 January 2011

DOI:https://doi.org/10.1103/PhysRevB.83.245434