Microstructure and Electrical Properties of Nonstoichiometric Strontium Titanate Thin Films Grown on Platinum Electrodes

Abstract

Nonstoichiometric strontium titanate films with the Sr/Ti ratio ranging from 0.9 to 1.4 were grown on Pt electrodes fabricated on Si substrates (Pt/Ta/SiO 2 /Si) by the RF-sputtering method with low and high deposition temperatures (250°C and 600°C, respectively). The insulating and dielectric properties of nonstoichiometric SrTiO 3 films have been studied as a function of Sr/Ti ratio. The highest dielectric constant was obtained by a SrTiO 3 film with a slight excess of SrO independent of the deposition temperature; the film showed better insulating property in comparison with the stoichiometric specimen, while the insulating property of TiO 2 -excess SrTiO 3 films, consisting of SrTiO 3 crystalline phase and Ti excess amorphous phase, notably depended on the deposition temperature. The high-temperature deposition resulted in better insulative resistance.