Elaboration and growth study of epitaxial SnO2 thin films deposited on (0001) Al2O3 substrates by sol-gel process

International audienceIn the form of thin films, SnO2 finds applications as gas sensors, solar cells and transparent electrodes. The application of SnO2 for functional wide bandgap semiconductors requires highly crystalline epitaxial films [1]. Since SnO2 is unstable at high temperatures, the preparation of epitaxial SnO2 thin layers requires a careful optimisation of processing temperature. Moreover, in the case of sol-gel processing of thin films, post-deposition thermal annealing induces the film islanding and the exaggerated growth of those islands having the lowest interfacial energy [2].In this communication, we present the elaboration and the microstructural characterization of SnO2 films prepared from two different tin oxide precursor solutions: tin (IV) isopropoxide Sn(OC3H7i)4 in a mixed solvent (toluene + isopropanol) and an alcoholic solution of modified SnCl2,2H2O. The thin films were grown by dip-coating on (0001) sapphire substrates. After drying, a first thermal treatment at medium temperature induces the crystallization of tin oxide. High temperature treatment induces grain growth and the formation of textured films. The microstructure of both polycrystalline and textured films has been studied by conventional and high resolution XRD, AFM and TEM.[1] L.C. Tien, D.P. Norton, J.D. Budai, Mat Res Bul, 2009, 44, 6-10.[2] R. Bachelet, S. Cottrino, G. Nahélou, V. Coudert, A. Boulle, B. Soulestin, F. Rossignol, R. Guinebretière, Nanotechnology, 2007, 18, 015301 (9 pages)