Field-effect modulation of the transport properties of nondoped SrTiO3

We have fabricated SrTiO3 (100) single crystal field-effect transistors with amorphous and epitaxial CaHfO3 gate insulator layers. The devices with amorphous insulator layers showed nearly temperature independent behavior. The transistors with epitaxial interfaces exhibited a large improvement over the amorphous devices. The field-effect mobility was found to increase at low temperature, reaching 35cm2∕Vs at 50K. This result shows that the carriers accumulated by the field effect on the SrTiO3 side of the gate interface behaved as would be expected for electron-doped SrTiO3. An insulator-metal transition, induced by field-effect doping, was observed in epitaxial SrTiO3-based transistors.