Electric double layer transistors with ferroelectric BaTiO3 channels

We report the surface conduction of a BaTiO3 thin film using electric double layer transistor (EDLT) structure. A transistor operation was observed at 220 K with an on/off ratio exceeding 105, demonstrating that ionic liquid gating is effective to induce carriers at the surface of ferroelectric materials. Temperature dependence of channel resistance exhibited a metallic behavior down to 150 K. EDLT structure is also fabricated using a commercial BaTiO3 bulk single crystal for comparison, which shows abrupt resistance increase across the orthorhombic to rhombohedral transition temperature at 183 K. This result indicates that the epitaxial strain is effective to maintain low resistance in this material with keeping the single domain structure.