The Structure and Energy of Oxygen Vacancy Formation in Clean and

J. Phys. Chem. C 2007, 111, 12715-12722

12715

The Structure and Energy of Oxygen Vacancy Formation in Clean and Doped, Very Thin Films of ZnO Raj Ganesh S. Pala and Horia Metiu* Department of Chemistry and Biochemistry, UniVersity of California, Santa Barbara, California 93106-9510 ReceiVed: May 4, 2007; In Final Form: June 22, 2007

We use density functional calculations to study the structure and the energy of formation of the surface oxygen vacancy (VO) in a free-standing, very-thin film (VTF) of ZnO and substitutionally doped ZnO VTF. We are interested in this system because the walls of very high area oxides used in catalysis contain VTFs. We find that the structure of the ZnO(0001h) VTF is strongly dependent on the film thickness. Decreasing the thickness of the ZnO(0001h) VTF increases the distances between the atomic planes along the (0001h) direction. At a film thickness of five layers (L), the energy of the VTF with a wurtzite structure is the same as the energy of the VTF with a hexagonal structure. For thickness