Metal-Insulator-Superconductor Field-Effect-Transistor Using SrTiO3/YBa2Cu3Oy Heteroepitaxial Films

Planar-type metal-insulator-superconductor field-effect-transistors (MISFET) were fabricated and their current modulation characteristics were investigated. The FET had a structure of Al-gate metal/(100)SrTiO3-gate insulator/(001)YBa2Cu3Oy-channel, where the oxide layers were grown by selective heteroepitaxy employing pulsed ArF excimer laser deposition. The FET gate was 10 µm long and 100 µm wide. Apparent field-effect modulation of drain current was seen in both the normal (T>Tc) and superconducting (T<Tc) states. In the superconducting state, not only the critical current but also flux-flow resistance were appreciably changed according to the applied gate voltage.