The effects of different coverage of Nitrogen adsorbed on wurtzite ZnO(0001) surface

The adsorption of nitrogen on wurtzite ZnO (0001) surface were studied by First-principles. Different adsorption sites and the effect of different coverages have been considered. The clean ZnO (0001) surface and different coverages of Nitrogen adsorbed on wurtzite ZnO(0001) surface show n-type conduction. We found that the H3 adsorption site is energy-favored in each coverage considered, and that 0.25 and 0.5ML N adsorption leads to an indirect band gap semiconducting surface. Analyzing the electronic structures and the density of states of the adsorbed systems, we proposed that the strong hybridization between the Zn-3d and N-2p results in the consequent saturation of Zn dangling bonds and the formation of a polarized covalent Zn-N bonding. Our study may be able to provide a guidance for the growth of N-doped ZnO.