Single and multiple excitation of bulk and surface plasmons on clean ZnO surfaces

Abstract

Electron energy loss measurements in reflection with primary energies between 80 and 900 eV have been performed on clean cleaved ZnO polar {0001} and nonpolar {11̄00} surfaces in ultrahigh vacuum (p<10−10 Torr). The identification of surface and bulk plasmon loss peaks is possible from the observation of multiple losses and from the dependence of the spectra on primary energy. Surface and bulk plasmon excitation energies are obtained to be at 16 and 18.5 eV, respectively.