| 摘要 |
PURPOSE:To reduce the noise and realize a high speed operation and a high gain by a method wherein a device is operated while it is maintained at a temperature not higher than 77K and an electromagnetic wave such as a light, an ultraviolet ray, an infrared radiation, and an X-ray is applied to control the characteristics. CONSTITUTION:A device is maintained at a cryogenic condition (4.2K) in liquid helium and a light signal 8 with a wavelength of 632.8 nm is applied through an optical fiber 11. By this light application, an exciting phenomenon is induced in an electron supplying layer 3 and the surface electron concentration and the electron mobility of secondary electron gas are increased. Therefore, superconducting electron pairs penetrate into a semiconductor channel layer 2 from source and drain electrodes 5 and 6 which are superconductors and a superconducting current flows between the source and drain electrodes. On the other hand, the resistances between the source and a gate and between the gate and the drain are reduced and the cut-off frequency of the transistor is increased and the noise level is declined. Moreover, the switching speed, expressed by a time constant, is also increased. The increased electrons are maintained even if the application of the electromagnetic wave is discontinued as long as the temperature is maintained at as low as 77K or lower.
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