Nanoparticle-sintered BaTiO₃ thin films and its orientation control by solid phase epitaxy

A novel powder-sintering thin-film process using nanocrystals of sol-gel-derived BaTiO₃ without sintering additives yields a highly densified microstructure containing columnar grains at low temperatures of 800°C. The BaTiO₃ thin film fabricated on a (111)-oriented Pt/TiO₂/Al₂O₃ substrate shows high crystallinity and a relatively high dielectric constant of 635 at 10 kHz with a low loss tangent of 0.007. Furthermore, the controllability of the crystallographic orientations of thin films by solid phase epitaxy is demonstrated on the basis of the optimization of surface nucleation and the subsequent grain growth on epitaxially grown platinum electrodes and single-crystal SrTiO₃ substrates.