SUPERCONDUCTING PHASE-CHANGE TYPE FET

PURPOSE:To realize a FET having for larger mutual conductance than the High Electron mobility Transistor (HEMT) heretofove in use. CONSTITUTION:After the first buffer layer 12 composed of an insulation layer containing SiN, etc., on a substrate 11 containing SrTiO3, the first and second semiconductor layers 13 and 14 containing N -GaAs, etc., are formed facing each other thereon in a specified interval and a superconductive layer 15 containing TlBa2Ca3Cu4O11, etc., is formed between the layers 13 and 14. Next, the insulation layers 16 and 17 containing SiO2 etc., are built in a superconductive layer 15, and the second buffer layer 21 composed of insulators such as SiO2, etc., on the layers 13 and 14, and the layer 15. Further, a source electrode 25 and drain electrode 26 are Prepared on the layer 21 so as to be piled up on the layers 13 and 14, respectively. On the other hand, a source electrode 27 is prepared on the layer 21 so as to be piled up on the layers 16 and 17.