Structure formation and electrical properties of thin films: The Ce-Ti-O system

Recently Nagarajan et al. found a new type of chemically driven insulator-metal transition in non-stoichiometric gallium oxide films (GaOx) [1]. Leichtweiß et al. [2] showed a similar behavior for non-stoichiometric titania (TiO1.6) films. Both oxides disproportionate during heating and relax into the thermodynamically stable phases. A similar approach has been applied to ternary oxides like ITO [3]. Davila et al. produced a nanocomposite and highly oxygen deficient ITO film. Due to its non-stoichiometry the thin film separates directly into a stoichiometric matrix (In1.8Sn0.2O3) which contains metallic clusters (In1.8Sn0.2). This can be explained by the absence of stable suboxides in the system In-Sn-O. Figure 1 highlights the general experimental approach: Depositing metastable and non-stoichiometric oxide thin films followed by a heating step makes it possible to study the reaction pathways during relaxation into the thermodynamically stable state by various in and ex situ techniques. Please click Additional Files below to see the full abstract