Photoelectron spectroscopic study on electronic state and electrical properties of SnO₂ single crystals

Electronic states and band bending behavior of SnO₂ single crystals grown by physical vapor transport were investigated by combining surface-sensitive soft-and bulk-sensitive hard X-ray photoelectron spectroscopy (PES). The as-grown SnO₂ crystals had a higher density of in-gap states relating to oxygen vacancies in comparison with the SnO₂ crystal annealed at 1100 °C under oxygen atmosphere. Both samples have similar Fermi level pinning at 0.26 eV below the conduction band minimum at the surface and no surface accumulation layer. The estimated carrier density by PES at the surface of the as-grown and annealed SnO₂ crystals were 3.2 × 10¹⁷ and 3.2 × 10¹⁵ cm^-3, respectively.