HYDROTHERMAL STRONTIUM-TITANATE FILMS ON TITANIUM - AN XPS AND AES DEPTH-PROFILING STUDY

SrTiO3 films in the 100-nm thickness range were grown on Ti foils by a 2-4 h hydrothermal treatment at 225-degrees-C in an aqueous solution of Sr(OH)2. X-ray diffraction showed the principal reflections of cubic SrTiO3. Photoelectron analysis revealed the presence of carbon contamination and suggested the presence of hydroxyl groups on the surface, which disappeared in the film bulk. The Auger depth profiles showed three distinct zones. The outermost layer, besides the common carbon contamination, had a large number of OH groups. The second zone was a clean, almost carbon-free SrTiO, film. The third zone was a diffuse interface region where the Sr and O concentrations slowly decreased toward the substrate.