Abstract: A transmission photocathode comprising a crystal substrate transparent to the radiation to be detected, at least one epitaxial crystalline intermediate layer having a lattice constant close to that of the detector layer and transparent to the radiation to be detected, and a p-type group III-V compound detector layer. Preferably the intermediate layer is p-type.

Abstract: A switching device equipped with a semiconductor memory element in which the semiconductor memory element includes at least one junction region provided on a semiconductor base plate, a thin insulating film through which carriers can pass and an insulating film having a trap level, said two insulating films being disposed on the surface of said semiconductor base plate in stacked layer relationship, thereby providing a memory function. The present device is provided with this semiconductor memory element, a power supply for controlling the semiconductor memory element and means for turning on or off the controlling power supply, thus accomplishing a touch-switching device of high impedance and ensuring its operations with inexpensive cost.