Infrared spectroscopy of strained BaTiO3/SrTiO3 superlattices on scandate substrates

Polarized infrared reflectance of ferroelectric [(BaTiO)/(SrTiO)] superlattices grown on DyScO, TbScO, EuScO and SmScOsubstrates by reactive molecular beam epitaxy was measured. Infrared spectra (30–3000 cm) were taken independently from the (110) cut of bare substrate and the substrate covered with superlattice in two polarizations: along the -axis and perpendicular to it. The phonon parameters and dielectric function of the superlattice were extracted using a fitting procedure to study the influence of the strain induced by different substrates. The phonon frequency dependence on the substrate-induced strain was varying from 75 to 95 cm. The superlattice static permittivity was estimated from that data, which varies from 150 to 270 depending on substrate and polarization. The highest permittivity was obtained for the EuScO substrate.