Increasing the spectral separation between the emission lines from individual CdSe quantum dots through annealing

An annealing process has been applied during the growth of CdSe/ZnSe quantum dots (QDs). The annealing was able to spectrally separate the photoluminescence (PL) emission of two types of dots in the sample by as much as 160 meV. In a μ-PL study we found that the spectral separation between the emission peaks from individual QDs in the spectral region corresponding to the low energy ensemble PL feature had been significantly increased by the annealing. Despite not having directly affected the dot density, by defining a spectral window of 50 meV, based on the full-width at half-maximum (FWHM) of the ensemble PL of the normally grown sample, we have reduced the number of dots in the window from several thousand to approximately 10 making it possible to isolate the emission of single QDs for further study.