METHOD FOR THE UNIFORM CHEMICAL VAPOR-DEPOSITION OF TIN-DOPED INDIUM SESQUIOXIDE FILMS ON CYLINDRICAL SUBSTRATES

One of the applications of electrically conductive tin-doped indium sesquioxide films is as the air electrode current collector material in a high temperature thin film fuel cell power device. For this application it is necessary to produce films of reproducible uniform thickness and composition on tubular ceramic substrates; this requirement prompted the development of the chemical vapor deposition (CVD) method described in this paper. The method was based on the high temperature hydrolysis of the chloride and oxychloride vapors of tin and indium. A single reactor was employed both for the generation of these vapors and for their hydrolysis reaction. The dimensions of this reactor allowed the formation of films of reproducible and uniform thickness and composition on tubular substrates 25 cm long and of external diameter 1.27 cm. The films, produced on calcia-stabilized zirconia and alumina substrates, were characterized by electrical resistance measure'ments, chemical analysis and microscopic examination. The room temperature resistivity of the as-prepared films was close to 2.0 × 10-4 Ω cm for thicknesses ranging from 20 to 50 μ. Information on the temperature dependence of the resistivity of annealed films on the calcia-stabilized zirconia substrate is also presented. © 1979.