Structural Study of Tin‐Doped Indium Oxide Thin Films Using X‐Ray Absorption Spectroscopy and X‐Ray Diffraction: I . Description of the Indium Site

Abstract

Thin films of tin‐doped , with different tin contents produced by a powder pyrolysis technique have been investigated by x‐ray absorption spectroscopy and x‐ray diffraction. At the indium K‐edge, extended x‐ray absorption fine structure (EXAFS) investigations reveal that the indium atomic environment is modified by the doping. Even at low tin concentrations, the first oxygen polyhedron and the metallic In‐In coordination shells are disordered. This disorder increases with increasing tin content, and, for a large tin content (39% Sn), the In‐O shell is locally similar to that of the hexagonal high pressure phase of , that is also known to be stabilized at atmospheric pressure by the insertion of small foreign cation (such as Sn4+) in the indium oxide structure. The x‐ray diffraction experiments also support the idea of a disordered network; the x‐ray reflections decrease in magnitude but remain sharp even for a high tin concentration. This indicates that the structural disorder observed by EXAFS only induces a damping of the x‐ray reflections (the network is still ordered within large domains). The following modifications of the host network were observed; an increase in the lattice parameter, a decrease in the size of coherence of the diffraction domains with increasing the tin content (from 1200 Å to 700 Å), and a <100> preferential orientation, which disappears for the high dopant concentrations.