CURRENT SELF-OSCILLATIONS IN PHOTOEXCITED TYPE-II GAAS-ALAS SUPERLATTICES

Self-oscillations of the photocurrent have been observed in type-II Ga As-AlAs superlattices. In addition to the fundamental frequency, sever al higher harmonics are present. The frequency of the oscillations can be tuned for a fixed carrier density from 15 to 120 MHz by simply cha nging the applied bias. The frequency distribution within a certain vo ltage range can be varied by changing the density of photoexcited carr iers. For larger carrier densities, higher frequencies are observed in a different voltage range. This system could therefore be used as a h igh-frequency oscillator, which can be controlled by two external para meters, the applied voltage and the light intensity. (C) 1996 American Institute of Physics.