Dielectric properties of sputtered SrTiO3 films

The dielectric properties of 100-oriented epitaxial SrTiO3 films as used in high-Tc heterostructures have been studied as a function of temperature and applied electric field by using in situ grown heterostructures (Mg/SrTiO3/SrTiO3 and Au/YBa2Cu3O7-x/SrTiO3/SrTiO3). 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/m2 at 4.2 K. Complementary measurements on single crystals of SrTiO3 and SrTiO3 reveal that the behavior of these SrTiO3 thin films can be understood from the bulk properties with additional strong charge trapping at the film-substrate interface. © 1994 The American Physical Society.