Trapping of photogenerated carriers by InAs quantum dots and persistent photoconductivity in novel GaAs/n-AlGaAs field-effect transistor structures

Abstract

The trapping of photogenerated carriers by embedded InAs quantum dots (QDs) has been studied at 77 K in novel GaAs/$n$ -AlGaAs structures. It is found that the concentration $N_s$ of two dimensional electrons at a given gate voltage $V_g$ is persistently increased by light illumination, because of the trapping of holes by QDs. By the interplay of the gate voltage and photocarrier generation, a distinct hysteresis is observed in the $N_s$ -$V_g$ characteristics. A drastic change of electron mobility by a factor of 19 is achieved by light illumination. The applications of this device for a novel light-controllable floating dot memory is suggested.