Stability of Magnesium-Incorporated Semipolar GaN(10(1)over-bar(1)over-bar) Surfaces

The stability of Mg-incorporated GaN surfaces with semipolar (10 (1) over bar(1) over bar) orientation is investigated by performing first-principles pseudopotential calculations Several Mg-incorporated surfaces, in which a single Mg atom is substituted for the topmost Ga atom, can be formed when the surfaces include step edges in the [0 (1) over bar 00] direction. This implies that on the stepped surfaces Mg atoms can be easily incorporated into electrically active substitutional lattice sites leading to high hole concentrations. The calculated results provide a possible explanation for experimentally observed high hole concentrations in Mg-doped semipolar (10 (1) over bar(1) over bar) GaN on vicinal (100) MgAl2O4 substrates miscut in the < 011 > direction. (C) 2009 The Japan Society of Applied Physics