Temperature-dependent micro-photoluminescence of individual CdSe self-assembled quantum dots

Abstract

CdSe quantum dots embedded in a ZnSe matrix have been known to exhibit temperature-dependent excitonic emission. This phenomenon is studied using micro- and nanophotoluminescence. The influence of temperature on ultranarrow emissions from excitons confined to a single quantum dot, as well as statistical ensembles of up to 200 dots, was observed by changing the spatial resolution from 200 nm to 1.7 μm. Measurements of PL quenching with temperature reveal two different kinds of states responsible for the observed PL emission. In addition to the previously observed broad PL line persisting to 300 K with an activation energy around 40 meV, ultranarrow lines quenched at about 60 K with an effective activation energy of only 4.0 meV were found.