Comparative XPS and PYS studies of SnO2 thin films prepared by L-CVD technique and exposed to oxygen and hydrogen

The electronic properties of the space charge layer of the tin dioxide thin films, prepared by the laser-induced chemical vapour deposition (L-CVD), have been studied using X-ray photoelectron spectroscopy (XPS) and photoemission yield spectroscopy (PYS). Based on the analysis of Sn3d5/2 XPS peak, the influence of exposition to molecular oxygen O2 and hydrogen H2 on the stoichiometry of the L-CVD deposited SnO2 thin films, as well as the interface Fermi level position in the band gap, have been determined and compared to the variation of the work function determined from the threshold of the ex situ recorded photoemission yield spectra. The observed changes of the interface Fermi level and the work function upon adsorption/desorption of O2 and H2 were attributed to decrease/increase of the concentration of oxygen vacancies in the near surface region.