Field-effect modulation of the transport properties of nondoped SrTiO3

Abstract

We have fabricated $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ (100) single crystal field-effect transistors with amorphous and epitaxial $\mathrm{Ca}\mathrm{Hf}{\mathrm{O}}_3$ 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 $35{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ at $50\mathrm{K}$ . This result shows that the carriers accumulated by the field effect on the $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ side of the gate interface behaved as would be expected for electron-doped $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ . An insulator-metal transition, induced by field-effect doping, was observed in epitaxial $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ -based transistors.