CdSe quantum dots grown on a Zn0.2Mg0.8S0.64Se0.36 barrier: MBE growth and μ-PL characterisation

Abstract

We report the growth and characterisation of CdSe quantum dots grown by MBE with Zn0.2Mg0.8S0.64Se0.36 barriers and their subsequent characterisation by 77K PL and 4Kμ-PL. The 4Kμ-PL spectra showed numerous peaks having spectral diffusion on a timescale of <25ms. By correlating the variation in peak energies and intensities we are able to assign which transitions arise from individual dots and hence count the number of distinguishable dots within the resolved spot of the microscope system. This is found to be consistent with a dot density of 4±1×1010cm−2.We also discuss the possible mechanism behind the spectral diffusion seen in these measurements. Correlation of emission intensity from single-dot emission lines was also observed over much longer time periods (∼200s). These results will be compared with previous results from CdSe dots grown on ZnSe barriers.