Reconstructions of GaN and InN Semipolar (10(1)over-bar(1)over-bar) Surfaces

We report a systematic and comprehensive investigation of reconstructions of semipolar GaN(10 (1) over bar(1) over bar) and InN(10 (1) over bar(1) over bar) surfaces by first-principles total-energy calculations. The surface formation energy indicates that there are several reconstructions depending on the growth conditions: The 1 x 2 surface consisting of a single Ga-Ga dimer and Ga vacancies is stable under N-rich conditions, whereas metallic reconstructions are favorable under Ga-rich (In-rich) conditions. We also characterize atomic structures of semipolar surfaces under realistic growth conditions using surface phase diagrams. For InN, the analysis of density of states predicts charge accumulations on semipolar surfaces. (C) 2009 The Japan Society of Applied Physics