XPS study of the L-CVD deposited SnO2 thin films exposed to oxygen and hydrogen

In this paper, the XPS study of SnO2 thin films deposited by the L-CVD technique are presented. The influence of exposition of the as-deposited samples to oxygen O-2 and hydrogen H-2 on their stoichiometry was determined. Moreover, on the basis of detailed shape analysis of the Sn3d(5/2) and Ols XPS peaks, the chemical shift of binding energy corresponding to the change of sample stoichiometry was separated from a shift of the binding energy corresponding to the change of interface Fermi level position E-F-E-v in the band gap, using a new procedure of deconvolution of the core level XPS peaks. The shift of the Sn3d(5/2) peak by approximately 0.5 eV towards the lower binding energy after highest H-2 exposure was interpreted as a true chemical shift due to an increase of Sn2+ component, whereas the shift of Sn3d(5/2) peak and Ols peak after highest O-2 exposure by approximately 0.5 eV towards the lower binding energy was interpreted as a result of the shift of the interface Fermi level position in the band gap towards the top of valence band at the surface, which corresponds to a deep accumulation layer typical for SnO2 thin films. (C) 2001 Elsevier Science B.V. All rights reserved.