Random telegraph noise in photoluminescence from individual self-assembled quantum dots

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Abstract
We have performed photoluminescence microscopy studies of spatially resolved quantum dots grown by the Stranski-Krastanow technique. A small fraction of the dots (one in about a thousand) has been found to exhibit an intermittence, with their emission intensity switching between discrete levels on a time scale of seconds. The statistics of the switching corresponds to a random telegraph signal and the frequency increases superlinearly with excitation power density. The intermittence can be irreversibly suppressed by strong illumination. Emission spectra of these dots show significant differences between the on-state and the off-state. The observed switching behavior is attributed to mobile photoactivated nonradiative recombination centers.