Control of misfit strain in ferroelectric BaTiO3 thin-film capacitors exploiting multi buffer layers

摘要

Because of a large lattice mismatch of ～ 2.3% between BaTiO3 and SrTiO3, an insertion of buffer layers such as (Ba, Sr)TiO3 beneath bottom electrodes is considered to be effective for improving polarization switching properties. Although BaTiO3 capacitors with SrRuO3 electrodes have been extensively studied, it remains unclear how a misfit strain is relaxed in BaTiO3 capacitors with a buffer layer and thereby influences their polarization properties. To understand the design principles of ferroelectric capacitors, high-resolution X-ray diffraction (XRD) structural analysis is required for heteroepitaxial films with the buffer layers having different lattice parameters combined with the characterization of polarization-electric field (PE) properties.