Spectroscopic studies of random telegraph noise in small InP quantum dots in GaxIn1-xP -: art. no. 073309

We have observed and investigated random telegraph noise in the photoluminescence (PL) from small InP quantum dots (QDs) in GaInP. Very few of the QDs exhibit switching between two states, which have similar total intensities, but distinctly different spectra. Usually, one of the states dominates at low excitation power and the other at high excitation power. The switching occurs on the time scale of one second and is stable with respect to annealing at room temperature, but the QDs can be permanently settled in one of the states by strong illumination. Measurements on QDs in a semitransparent Schottky diode show that the QDs can be reversibly forced into one of the states by applying a reverse bias of the order of 1 V. This switching behavior is different than what has been previously observed because there is no change in the total PL intensity and, at the same time, both states cannot be explained as simply being shifted by an electric field, but show distinctly different emission spectra.