First-principles study of Mg incorporation at wurtzite InN (0001) and (0 0 0 (1)over-bar) surfaces

in this article we investigate the energetics of Mg adsorption and incorporation at the InN(0 0 0 1) and InN(0001) surfaces by the method of total energy plane-wave expansions with ultra-soft pseudo potential technology based on the density functional theory (DFT) in the generalized approximation (GGA). It is found that for a 1/4 monolayer (ML) coverage of the InN(0001) surface, Mg atoms preferentially adsorb at the bridge sites and T4 sites, but they are unstable when compared with Mg incorporated in the first three layers. For a 114 ML coverage of the InN(0001) surface, Mg atoms preferentially adsorb at the H3 sites with the formation energy of -3.49 (eV/(2 x 2) supercell), which is lower than that of the T4 sites, and the formation energy increases with increasing magnesium coverage. Further study shows that the formation energy for Mg atom is lower than that of In atom, which indicates that magnesium adsorption is more favorable in these conditions. (C) 2008 Elsevier B.V. All rights reserved.