STRUCTURAL STUDY OF TIN-DOPED INDIUM OXIDE THIN-FILMS USING X-RAY ABSORPTION-SPECTROSCOPY AND X-RAY-DIFFRACTION .2. TIN ENVIRONMENT

Thin films of tin-doped In2O3 (ITO for indium tin oxide) with different tin contents produced by a powder pyrolysis technique have been investigated by x-ray absorption spectroscopy and x-ray diffraction. In a previous paper, an extended x-ray absorption fine structure (EXAFS) study at the indium K-edge and diffraction measurements were presented. From the EXAFS investigations at the indium edge, it has been shown that the indium atomic environment becomes comes disordered during the doping process. In the present work, the EXAFS results at the tin K-edge and x-ray diffraction data are discussed. Both methods show that the tin solubility in the film is higher than in the powder form of ITO. The EXAFS study confirms that the tin atoms are located at indium sites as inferred from the electrical properties of ITO. Also observed is a relaxation of the first oxygen polyhedron around the dopant atoms that increases with the tin content. The disorder of the host network and of the tin metallic environment is clearly related to the changes observed in the Sn-O shell.