Dielectric property of BaTiO3-SrTiO3 artificially modulated structure made by MBE

In order to elucidate the origin of the asymmetry observed in the D-E or C-V hysteresis loops of BaTiO₃(BTO)-SrTiO₃(STO) epitaxial films, “artificially modulated structures” (AMSs), where the chemical composition was continuously changed along the direction of film thickness, were prepared and their dielectric properties were measured. A fully automatic molecular beam epitaxy system was developed to fabricate AMSs. The simulation of XRD profiles indicated that a relaxation of the crystal lattice occurred along the a-axis in the two AMSs. It was observed that the asymmetry of the C-V hysteresis loop was changed by the modulation, and that the origin of the asymmetry was attributed to the lattice relaxation rather than the asymmetry of the stress field