Optical and electron-beam control of semiconductor switches

Two ongoing research projects on bulk semiconductor switches which can be closed and opened on command are described. Both types of switches have the advantage of requiring small energies to support the conductivity and switching action on a nanosecond time scale. The switch mechanism in one of the projects is based on laser quenching of photoconductivity in semiconductors containing certain deep level impurities. Investigators in GaAs and CdS crystals have demonstrated the quenching effect. The second project deals with electron-beam control of the semiconductor switch. The electrons are injected through a contact into the cathode region of a semiconductor switch. Through cathodoluminescence processes it is possible to obtain bulk ionization, thereby overcoming the space-charge limitations. A switch-current/electron-beam-current ratio of more than 1500 at current densities of 60 A/cm² has been achieved so far