SUPERCONDUCTIVE TRANSISTOR

PURPOSE:To increase the resistance between source and drain electrodes in the state a voltage is applied, to reduce leaking currents and to enhance gain in current, voltage and power, by inserting an insulating layer between a semiconductor layer and a superconductive electrode, thereby reducing the contacting area of both parts. CONSTITUTION:The surface of an Si substrate 1 is thermally oxidized, and an insulating layer 8 comprising SiO2 is formed. By a DC magnetron sputtering method, Nb thin films 5 and 7 and an SiO2 interlayer insulating film 11 are sequentially deposited. They are isolated into a source electrode 6 and a drain electrode 5. The insulatings films 11 are formed on the respective electrodes. Then a channel layer 10 comprising an Si semiconductor is formed. Thereafter, an insulating film 7 comprising SiO2 is formed by a thermal oxidation method. Thereafter, a control electrode 9 comprising Nb is formed. When the insulating layers 11 are inserted in this way, since the contacting area of the superconductive electrodes 5 and 6 and the channel layer 10 is small, the resistance between the source and drain electrodes in the state a voltage is applied becomes large, and leaking currents are decreased.