Electrical detection of optically induced charge storage in self-assembled InAs quantum dots

Spectrally resolved photoresistance investigations of charge storage effects in self-assembled InAs quantum dots (QDs) are reported. Resonant optical excitation of the QDs produces a strong increase of the lateral resistance of a spatially separated electron channel $\mathrm{(\Delta R)}$ which reflects the stored charge density. This photoresponse is persistent for many hours at 145 K and can be controllably reversed electrically. Pronounced oscillations observed in the spectral variation $\mathrm{\Delta R}$ are shown to reflect the excitation spectrum of the QD ensemble showing resonances that arise from both direct and phonon-assisted absorption processes.