Energetics of Mg, B, Cu, and Ti atoms adsorbed on the ZnO polar surfaces from

Abstract

Using the density functional theory we have studied the energetics of the adsorbed atoms, Cu and Ti, on the (0001) zinc and (0001̄) oxygen polar surfaces of zinc oxide (ZnO). We have revisited the energetics of Mg and B atoms on the surfaces (Phys. Rev. B 77 035330 (2008)) and investigated them in connection with those of Cu and Ti. On the Zn polar surface, B and Ti atoms are adsorbed on the hcp site and are strongly bound to the oxygen atoms in the subsurface. Mg atom preferably binds to the three oxygen atoms on the O polar surface in the distances of 2 Å. Cu atom is also adsorbed on the Zn surface. We found an energy barrier 0.17 eV for the Cu migration along the path from the fcc site to the hcp site on the Zn surface. After the structural relaxation, Ti atom on the O surface infiltrated into the subsurface region and fitted into the tetrahedral cage made of the four oxygen atoms. Our results are consistent with the available experimental data and explain their energetics in atomic scale. Determinant factor of their preference of the sites is investigated. © 2011 The Surface Science Society of Japan.