Adsorbed-H Induced Metallization of ZnO(10(1)over-bar0) Surface

The adsorption energy, density of states (DOS) and band structure of H on a ZnO(10 (1) over bar0) surface were studied using the first-principles projector-augmented-wave (PAW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA) and the supercell model. It was found that.: 1) For H adsorbed on ZnO(10 (1) over bar0) (denoted ZnO(10 (1) over bar0) only the OH group was formed and the ZnH species was not detected, The unoccupied Zn 4s electronic state receives an electron and renders the surface metallic. DOS and the band structure show that the Zn 4s electronic state in the conduction band (CB) receives electrons and migrates toward the forbidden band so that overlapping of the CB and valence band (VB) below the Fermi level is observed. 2) When 2H are adsorbed, the ZnO (10 (1) over bar0) is denoteds ZnO(10 (1) over bar0)-2H. On the surface of ZnO(10 (1) over bar0)-2H two Hs are adsorbed separately on Zn and O and the two dangling bonds on the surface are saturated. The analysis of DOS and band structure of the ZnO(10 (1) over bar0)-2H Surface shows that it is the same as a clean ZnO(10 (1) over bar0) surface and that both are insulating surfaces.