Crystal Orientation Control of Bismuth Layer-Structured Dielectric Films Using Interface Layers of Perovskite-Type Oxides

Thin films of SrBi(4)Ti(4)O(15), a kind of bismuth layer-structured dielectrics (BLSDs), were prepared on platinized silicon wafers buffered by perovskite-type oxide interface layers, (100)LaNiO(3)/(111)Pt/TiO(2)/(100)Si and (001)Ca(2)Nb(3)O(10)-nanosheets/(111)Pt/TiO(2)/(100)Si, by chemical solution deposition (CSD). The Ca(2)Nb(3)O(10) nanosheets were supported on a (111)Pt/TiO(2)/(100)Si substrate by dip coating using an aqueous dispersion, while (100)LaNiO(3) was prepared by CSD. The (00/) planes of BLSD crystal were preferentially oriented on the surface of both substrates, which is caused by suitable lattice matching between the a-(b-)axis of BLSD and perovskite-type oxide layers. The film deposition on (001)Ca(2)Nb(3)O(10) nanosheets yielded (001)-oriented BLSD films with higher crystallinity and smaller fluctuation in the tilting angle of the (001)BLSD plane than those on the (100)LaNiO(3) interface layer. The dielectric constant (epsilon(r)) of (001)-oriented SrBi(4)Ti(4)O(15) film on (001)Ca(2)Nb(3)O(10)-nanosheets/(111)Pt/TiO(2)/(100)Si substrate was approximately 190, which was significantly stable against the change of frequency and bias voltage compared with that of the randomly-oriented SrBi(4)Ti(4)O(15) film. (C) 2011 The Japan Society of Applied Physics