Scanning Tunneling Spectroscopy Study of the ZnO(0001)?Zn Surface

The electronic structure of the ZnO(0001)–Zn surface was studied using scanning tunneling spectroscopy (STS) and first principles molecular dynamics. The STS spectrum indicated that the clean surface is n-type semiconducting with a band gap of about 3.3 eV. The local density of states (LDOS) calculated using ZnO slab model was in qualitative agreement with the STS spectrum, and revealed that occupied and unoccupied peaks originate from O and Zn atoms at the top bilayer of the surface, respectively. From the contour plots of LDOS, it was found that Zn atoms dominantly contribute to both occupied and unoccupied LDOS distributions and their broadening on the surface, which prevents atom-resolved scanning tunneling microscopy imaging of ZnO(0001) surface.