Thin films of bismuth layer-structured dielectrics (BLSDs), CaBi4Ti4O15, and SrBi4Ti4O15, were prepared by a chemical solution deposition (CSD) technique on various substrates, such as (111)Pt/TiO2/(100)Si, (100)LaNiO 3/(111)Pt/TiO2/(100)Si, and (100)SrRuO3//(100) SrTiO3 substrates. Conductive perovskite oxide LaNiO3 with (100) preferential crystal orientation was introduced into the interface between the BLSD film and the (111)Pt/TiO2/(100)Si substrate to control the crystal orientation of BLSD by lattice matching between pseudo-perovskite blocks in the BLSD crystal and the (100)LaNiO3 plane with the perovskite structure. The (00/) planes of BLSD crystals were preferentially oriented on the substrate surface of the (100)LaNiO 3/(111)Pt/TiO2/(100)Si, whereas randomly-oriented BLSD crystals with lower crystallinity were only obtained on the surface of (111)Pt/TiO2/(100)Si substrate. The (001)-oriented BLSD films exhibited the leakage current densities below 10-7A/cm2 at ±50 kV/cm, which is significantly lower than those for randomly-oriented films, above 10-6 A/cm2, The room-temperature dielectric constants (εr)p of CaBi4Ti4O15 and SrBi4Ti4O15 thin films on the (100)LaNiO3/(111)Pt/TiO2/(100)Si substrate were both approximately 250, while those on the (100)SrRuO3//(100)SrTiO 3 substrate were approximately 220. The temperature dependence of the capacitances for the CaBi4Ti4O15 and SrBi 4Ti4O15 films on the (100)LaNiO 3/(111)Pt/TiO2/(100)Si substrate were approximately+17 and +10%, respectively, in the temperature range from 25 to 400 °C. These values were slightly larger than those of epitaxial BLSD films, but smaller than those of (Ba,Sr)TiO3 films.
ASJC Scopus subject areas
- Physics and Astronomy(all)