Tin dioxide with the CaF 2 structure in thin oxide films

Abstract

Reflection high energy electron diffraction and depth-selective Mössbauer spectroscopy investigations of tin oxide films showed that the oxidation of the divalent tin oxide, which is crystallochemically analogous to SiO and is designated SnO(SiO), leads to the formation of a tin dioxide structure identical with that of CaF 2 which is designated SnO 2(CaF 2). This transition is due to the uniform contraction of the SnO(SiO) lattice. It is shown that the resistivities of thin tin oxide films consisting of SnO 2(CaF 2) textured along the [100] direction and SnO 2 (cassiterite) are very high (ϱ > 10 5 Ω cm) . Observation of the growth of SnO 2(CaF 2) on various substrates suggests that its formation is a property of the tin itself and is not a result of epitaxial growth on oriented single-crystal substrates.