SZ9-90-015 SUPERCONDUCTING FIELD-EFFECT TRANSISTORS WITH INVERTED MISFET STRUCTURE AND METHOD FOR MAKING THE SAME This field-effect transistor comprises a conductive substrate serving as the gate electrode, an insulating barrier layer, and a superconducting channel layer on top of the barrier layer. The superconductor layer carries a pair of mutually spaced electrodes forming source and drain, respectively. The substrate is provided with an appropriate gate contact. The substrate consists of a material belonging to the same crystallographic family as the barrier layer. In a preferred embodiment, the substrate is niobium-doped strontium titanate, the barrier layer is undoped strontium titanate, and the superconductor is a thin film of a material having a lattice constant at least approximately similar to the one of the materials of the substrate and barrier layers. A preferred material of this type is YBa2Cu3O7-.delta., where O ? .delta. ? 0.5.