title: Spectroscopy of single donors at ZnO(0001) surfaces.
abstract: Donors near the polar (0001) surface of nominally undoped ZnO were investigated with scanning tunneling microscopy at 5 K. Spatially resolved spectroscopy reveals single and double charging. Equidistant peaks in spectra of ionized donors are attributed to polaron excitation. The data are consistent with doping due to Zn interstitials or complexes.
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany. zheng@physik.uni-kiel.de
authors.forename: Hao
authors.initials: H
authors.lastname: Zheng
authors.forename: Jörg
authors.initials: J
authors.lastname: Kröger
authors.forename: Richard
authors.initials: R
authors.lastname: Berndt