Negative photoconductivity in double-barrier resonant tunneling diode

Abstract

We have used double-barrier, resonant tunneling diode to demonstrate a new bistable device that has both positive and negative photoconductive states. This bistable photoconductivity is brought about by the enhancement of the resonant tunneling effect in a double-barrier diode by light. Our double-barrier diode has only partial lateral current confinement, and, hence, the voltage across the double barrier varies laterally along the barrier plane. Because of this variation, the tunneling process is not simultaneously resonant across the entire double-barrier plane, leading to an increase in the valley current. By using light to increase the conductivity of the cap layer of the device, we can decrease the lateral voltage difference along the double-barrier plane and enhance the resonant tunneling effect. This enhancement leads to increased peak current and decreased valley current, thus achieving the bistable (positive and negative) photo-conductivity. Our theoretical model, which considers the partial lateral current confinement of the device, explains our experimental results.