Electrical and optical bistability in [111] GaInAs–GaAs piezo-electric quantum wells

Abstract

Optically induced bistability in the electrical and optical characteristics of a (111)B piezo-electric strained In0.15Ga0.85As–GaAs single quantum well (SQW) p-i-n structure is reported. We demonstrate that the bistability results from photo-induced charge build-up in the SQW. Charge build-up is enhanced relative to a (100) structure as a consequence of the modified band profile due to the large internal piezo-electric field. A region of hysteresis is observed in the low temperature current–voltage characteristics of the device under illumination. Dependent upon the sweep direction, for a given voltage the device is stable in one of two states, corresponding to either low or high current. Optical measurements demonstrate that the two current states correspond to very different electron densities in the SQW. An electron accumulation of n ns≈ 3.5× 1011cm−2occurs with the sample at 0∼V in the low current state. For the high current state there is negligible electron accumulation in the SQW. Using these values we have modelled the band profiles of the structure in the two bistable states.