Effects of surface relaxation on the electronic structure of ZnO (101̄0)

Abstract

We have investigated the effect of atomic relaxation on the electronic structure of the nonpolar ZnO (101̄0) surface using the tight binding scattering theoretical method. The bulk material is described by a realistic empirical tight binding Hamiltonian and the relaxation is taken into account by a d−2 scaling of the interaction matrix elements. We find that the ionic surface resonances and the covalent surface states, which we have reported about for the unrelaxed surface previously, are affected very differently by surface relaxation. The covalent surface states strongly shift in energy upon relaxation while the ionic resonances are only marginally affected. This result can easily be interpreted by correlating the changes in the surface electronic structure with the relaxation induced changes of the local binding environment near the surface. Our theoretical results are in good agreement with UPS and EELS data.