FIELD EFFECT DEVICE HAVING SUPERCONDUCTING CHANNEL

PURPOSE: To allow a channel to be in complete depletion state of charge carrier and form a switch of high ON/OFF current ratio by applying a control signal of proper strength to a gate because of sufficently thin superconductive channel. CONSTITUTION: A substrate 20 is formed of strontium/titanium oxide, and a channel 21 is made of high Tc superconductive material such as YBa2 Cu3 O7 and very thin, for example, about 1nm in thickness, and it is oriented within a plane parallel to the surface of the substrate so that the superconductivity may become the highest. When no gate voltage is applied, the channel 21 is in a superconductive state and an electric resistance between a source 22 and a drain 23 is zero. When a voltage is applied to a gate 25, the carrier concentration within the channel is changed by field effect. An extremely thin channel becomes in such a state short of carrier in an area under the gate because of sufficiently large voltage and appropriate polarity. Thus, a very high ON/OFF current ratio can be realized.