Optical charging of self-assembled InAs quantum dots

In this paper we describe the results of spectrally resolved photo-resistance investigations of optically induced charge storage in self-assembled InAs quantum dots. The results obtained demonstrate that, following resonant photo-excitation of the dots, excitons can be selectively ionised leaving either electrons or holes stored. This charge is sensed remotely using a density tuneable 2D electron - hole system and is shown to remain stored over very long timescales (>8 hours) at elevated temperature (similar to 150K). By analysing the temporal dependence of the charge storage effect, the optical absorption strength of the quantum dots is estimated to be similar to3.5x10(-5). The potential operation of the devices investigated as highly sensitive photo-transistors or a basic optical memory element is suggested.