Surface Reconstructions on GaN and InN Semipolar (20(2)over-bar1) Surfaces

The reconstructions on semipolar GaN(20 (2) over bar1) and InN(20 (2) over bar1) surfaces are investigated on the basis of first-principles total-energy calculations. The surface formation energy clarifies that there are several reconstructions depending on the growth conditions. For GaN, the surface where topmost N atoms are desorbed is stable under N-rich conditions, whereas a metallic reconstruction with a Ga adlayer is stabilized under Ga-rich conditions. For InN, in contrast, the surface with an In adlayer is favorable regardless of the growth conditions. We also provide immediate access to the atomic structures of semipolar (20 (2) over bar1) surfaces under realistic growth conditions using surface phase diagrams. (C) 2010 The Japan Society of Applied Physics