Resonant photoemission spectroscopic studies of SnO2 thin films.

We report the structural and electronic properties of single phase, polycrystalline rutile tetragonal SnO₂ thin film grown on Si (100) substrate by pulsed laser deposition technique. X-ray photoelectron and resonant photoemission spectroscopic (RPES) studies divulge that Sn is present in 4+(~91%) valence state with a very small involvement of 2+(~9%) valence state at the surface. Valence band spectrum of the film shows prominent contribution due to the Sn⁴⁺ valence state. RPES measurements were performed in the Sn 4d→5p photo absorption region. This study shows that O-2p, Sn-5s, and Sn-5p partial density of states are the main contributions to the valence band of this material. The resonance behavior of these three contributions has been analyzed. Constant initial state versus photon energy plots suggest that the low binding energy feature at ~2.8 eV results from the hybridization of the O-2p and mixed valence states of Sn, while remaining features at higher binding energies are due to the hybridization between O-2p (bonding) orbitals and Sn⁴⁺ valence state. [ABSTRACT FROM AUTHOR]