Three-terminal field effect superconducting device using SrTiO/sub 3/ 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 SrTiO/sub 3/ substrate. In the two-terminal devices, the Nb electrodes were coupled with an Nb-doped SrTiO/sub 3/ substrate with a carrier concentration of 2/spl times/10/sup 19/ cm/sup -3/. Electrode spacing was about 50 nm. The devices showed Josephson effect at 4.2 K. Three-terminal devices were made on a thinly doped surface of a non-doped 0.4-mm-thick SrTiO/sub 3/ 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 4.2 K.<>