Infrared quenching of conductivity at high electric fields in a bulk, copper-compensated, optically activated GaAs switch

Controlled compensation of silicon-doped gallium arsenide with copper has been obtained by a process of thermal annealing at ascending temperatures. By using compensated Cu:Si:GaAs as switch material it is possible to activate and deactivate photoconductivity with two laser pulses of different wavelengths. Persistent photoconductivity is first induced by 1064-nm radiation that is absorbed at copper centers in the bandgap. Later, the photoconductivity is extinguished by stimulating quenching with 1620-nm radiation. This process is shown to be temporarily effective against lock-on currents at fields greater than 3.5 kV/cm-that is after a delay of approximately 25 ns, the lock current reappeared at a lower magnitude, whereas, at low fields, the photocurrent was permanently quenched.< >