Dielectric properties of sputteredSrTiO3films

Abstract

The dielectric properties of 〈100〉-oriented epitaxial ${\mathrm{SrTiO}}_{3}$ films as used in high-${\mathit{T}}_{\mathit{c}}$ heterostructures have been studied as a function of temperature and applied electric field by using in situ grown heterostructures (Mg/${\mathrm{SrTiO}}_{3}$/${\mathrm{SrTiO}}_{3}$:Nb and Au/${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{x}}$/${\mathrm{SrTiO}}_{3}$/${\mathrm{SrTiO}}_{3}$:Nb). The dielectric behavior of these films is characterized by a rather low sample capacitance as compared to bulk single-crystal values and by occurrences of maxima in the capacitance-voltage and capacitance-temperature curves. The maximum attainable polarization was found to be 80 mC/${\mathrm{m}}^{2}$ at 4.2 K. Complementary measurements on single crystals of ${\mathrm{SrTiO}}_{3}$ and ${\mathrm{SrTiO}}_{3}$:Nb reveal that the behavior of these ${\mathrm{SrTiO}}_{3}$ thin films can be understood from the bulk properties with additional strong charge trapping at the film-substrate interface.