Detailed XPS and UPS studies of the band structure of zinc oxide

The X-ray photoelectron spectra of zinc oxide were measured in a wide range of quantum energies (30–150 and 1253.6 eV). It is shown that the form of the spectrum of the valence O2p-band depends on the energy of the incident quantum. The most probable reason for the change in the form of the O2p-band spectra is an admixture of Zn3d-electrons, which, along with Zn4s-electronst take part in covalent bonding of Zn and O. The dependence of the integral intensity ratio of the O2p-band to the intensity of the Zn3d peak on hv was analyzed, due to which the percent of the admixture of the Zn3d-states in the O2p-band was determined to be 9%. The stoichiometry and the depth of the profile of the concentration ratio were calculated taking into account the fraction of the Zn3d-electrons participating in the bond.