3 TERMINAL FIELD-EFFECT SUPERCONDUCTING DEVICE USING SRTIO3 CHANNEL

As a first step toward fabricating transistors to control supercurrent , we fabricated two- and three-terminal devices that have coplanar Nb electrodes coupled with a SrTiO3 substrate. In the two-terminal device s, the Nb,electrodes were coupled with an Nb-doped SrTiO3 substrate wi th a carrier concentration of 2x10(19) cm(-3). Electrode spacing was a bout 50 nm. The devices showed Josephson effect at 4.2 K. Three-termin al devices were made on a thinly doped surface of a non-doped OA-mm-th ick SrTiO3 substrate with gate electrodes on the non-doped area of the substrate. Resistance of the three-terminal devices was controlled by applying voltages to the gate electrode at 4.1 K.