The sapphire (0001) surface and the adsorption of ZnO are theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on density functional theory. By comparing the PDOS of the Al and the O before and after the surface relaxation, we demonstrate different apphire (0001) surface states, and changes in surface chemical bonding resulting from Al and O are analyzed. The bonding processing of a ZnO molecule on the surface of Al2O3, adsorption energy and bonding orientation, and change in surface structure as well as the characters of surface chemical bonding are further investigated. We conclude that the surface inward relaxation in the first layer Al-O is weakened, even eliminated after the surface adsorption of the ZnO; chemical bonding energy achieved 4.4±0.4 eV. There is a deflected angle of 30° between the chemical bonding of the ZnO s0.185±0.01 nmd and the adjacent surface Al-O bonding; the stable chemical adsorption site of Zn is just about 30 deflected from the O-hexagonal symmetry of the a-Al2O3s0001d surface. Through analysis of the atomic populations, density of state, and bonding electronic density before and after the adsorption, it is revealed that the chemical bonding formed by the O2− of the ZnO and the surface Al3+ is characterized by strong ionic bonding, while the bond of the Zn2+ and the surface O2− has a covalent character, which mainly comes from the hybridization of the Zn 4s and the O 2p and partially from the hybridization of the Zn 3d and the O 2p, so as to facilitate the forming of tetrahedral coordination in the initial stage of the ZnO films growth. Hence it is favorable for the formation of the wurtzite structure.

ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in the first layer Al-O is reduced, even eliminated after the surface adsorption of ZnO, and the chemical bonding energy is 434.3 (±38.6) kJ·mol−1. The chemical bond of ZnO (0.185±0.01nm) has a 30° angle away from the adjacent Al-O bond, and the stable chemical adsorption position of the Zn is deflected from the surface O-hexagonal symmetry with an angle of about 30°. The analysis of the atomic populations, density of state and bonding electronic density before and after the adsorption indicates that the chemical bond formed by the O2− of the ZnO and the surface Al3+ has a strong ionic bonding characteristic, while the chemical bond formed by the Zn2+ and the surface O2− has an obvious covalent characteristic, which comes mainly from the hybridization of the Zn 4s and the O 2p and partially from that of the Zn 3d and the O 2p.