Epitaxial SrTiO(3) films with dielectric constants exceeding 25,000

SrTiO(3) (STO) is an incipient ferroelectric perovskite oxide for which the onset of ferroelectric order is suppressed by quantum fluctuations. This property results in a very large increase in static dielectric constant from ∼300 at room temperature to ∼20,000 at liquid He temperature in bulk single crystals. However, the low-temperature dielectric constant of epitaxial STO films is typically a few hundred to a few thousand. Here, we use all-epitaxial capacitors of the form n-STO/undoped STO/n-STO (001) prepared by hybrid molecular beam epitaxy, to demonstrate intrinsic dielectric constants of an unstrained STO (001) film exceeding 25,000. We show that the n-STO/undoped STO interface plays a critically important role not previously considered in determining the dielectric properties that must be properly accounted for to determine the intrinsic dielectric constant.