Exciton dynamics of a single quantum dot embedded in a nanowire

International audienceWe have carried out a detailed optical characterization of a single CdSe quantum dot embedded in a ZnSe nanowire. Exciton, biexciton, and charged exciton lines have been identified unambiguously using photon correlation spectroscopy. This technique has provided a detailed picture of the dynamics of this system. It has been found that the dark exciton has a strong influence on the optical properties. The most visible influence is the strongly reduced excitonic emission compared to the biexcitonic one. Temperature-dependent lifetime measurements have allowed us to measure a large splitting of ΔE=(6.0±0.2) meV between the dark and the bright exciton as well as the spin-flip rates between these two states. This type of semiconducting quantum dot turns out to be a very efficient single photon source in the visible. Its particular growth technique opens additional possibilities as compared to the usual self-assembled quantum dots