Dark exciton optical spectroscopy of a semiconducting quantum dot embedded in a nanowire

TL;DR

This study investigates the optical properties of a single CdSe quantum dot in a ZnSe nanowire, revealing the significant role of dark excitons and their energy splitting with bright excitons through photoluminescence and temperature-dependent lifetime measurements.

Contribution

It provides new insights into dark exciton influence and quantifies the energy splitting and spin flip rates in a quantum dot embedded in a nanowire.

Findings

Dark excitons strongly influence optical emission.

Large energy splitting of 6 meV between dark and bright excitons.

Measured spin flip rates between exciton states.

Abstract

Photoluminescence of a single CdSe quantum dot embedded in a ZnSe nanowire has been investigated. 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 $\Delta E = 6 $ meV between the dark and the bright exciton as well as the spin flip rates between these two states.