Electron spectroscopic studies on films of SnO₂ and SnO₂:Sb

Abstract

Pure and antimony-doped SnO₂ films have been deposited by two different techniques: metal-organic chemical vapour deposition (MO-CVD) and spray pyrolysis of SnCl₄ in the presence of air with different concentrations of antimony. X-ray and UV photoelectron spectroscopic studies have been carried out on these films and the combined data from these studies provided information about the electronic properties of antimony-doped SnO₂ films and their compositions. That the binding energy of SnO is higher than that of SnO₂, contrary to expectations, is because of the fact that SnO₂ is more covalent than SnO. XPS has been used successfully to confirm the presence of Sb³⁺ and Sb⁵⁺ beyond a certain concentration of antimony (0.5 mol%) in the film, which is responsible for the decrease in conductivity and IR reflectivity. UV photoelectron spectroscopy of transparent, conducting SnO₂ films has been reported for the first time. The onset of photoemission in the valence band around 2.6 eV has been explained by invoking the idea of surface states near the valence band below the Fermi level.