Electronic structure, depth profile, and complex impedance spectroscopy of Pd doped ZnO ultrafine particle films

Abstract

Pd doped ZnO ultrafine particle (UFP) films were prepared by combining a direct current gas discharge activated reactive evaporation (direct current-gas discharge activated reactive evaporation) and a vacuum flashing evaporation technique. The electronic state structures and depth profiles of the Pd doped ZnO UFP films were investigated using angle resolved x-ray photoelectron spectroscopy. Three surface states of Zn 3d of Pd doped ZnO UFP films are observed, the positions of these states are located at 10.5, 5.5, and 2.7 eV, the binding energies at 10.5 and 5.5 eV result from Zn 3d state and Zn 4s–O 2p mixed state, the binding energy at 2.7 eV is mostly derived from O 2p, Zn 4p–O 2p or Zn 3d–O 2p. In addition, equivalent circuit of the Ag|Pd doped ZnO UFP film |Ag on the basis of morphology observed by scanning electron microscopy is established. Typical complex impedance spectroscopy at various temperatures is also used to study the Pd doped ZnO UFP film.