HRTEM observation of interface states between ZnO epitaxial film and Si(1 1 1) substrate

ZnO epitaxial thin films could be formed by oxidation of ZnS epitaxial thin films deposited on Si substrates by electron-beam evaporation. The orientation relation of the ZnO film was (0 0 0 2), [1 1 2 0]ZnO//( 1 1 1), [1 1 0]Si. The ZnS films were oxidized from its surface toward the surface of the Si substrate gradually. The ZnS film with a thickness of about 100 nm was completely changed to ZnO by annealing at 720 8C for 10 min in O2 atmosphere. By excess annealing, longer than 30 min, an intermediate layer was formed at the interface between the ZnO layer and Si(1 1 1) substrate. Exciton emission with a peak at 3.27 eV from ZnO became dominant and visible emission due to oxygen vacancy in ZnO disappeared by the annealing of the film at 800 8C for 5 h in O2 flow.