Quantitative analysis of the blue-green single-photon emission from a quantum dot in a thick tapered nanowire

TL;DR

This study provides a detailed quantitative analysis of blue-green single-photon emission from quantum dots in nanowires, revealing the effects of various excitonic processes and re-excitation mechanisms on emission properties.

Contribution

It introduces an analytical approach to simultaneously analyze decay curves and autocorrelation functions, offering new insights into exciton dynamics and re-excitation effects in quantum dot emitters.

Findings

Re-excitation from traps can fully control photon emission.

Re-excitation by mobile carriers or other QDs contributes as little as 5%.

Linewidths are measured at a resolution limit of 200 μeV.

Abstract

Quantum dots acting as single photon emitters in the blue-green range are fabricated and characterized at cryogenic temperature. They consist in CdSe dots inserted in (Zn,Mg)Se nanowires with a thick shell. Photoluminescence spectra, decay curves and autocorrelation functions were measured under nonresonant continuous-wave and pulsed excitation. An analytical approach is applied simultaneously to the decay curves and correlation functions. It allows a quantitative description of how these two quantities are affected by the exciton rise due to biexciton feeding, the bright exciton decay, the effect of the dark exciton, and the re-excitation between two laser pulses. Linewidths at our limit of resolution (200 $\mu$eV) are recorded. The reported correlation counts vary from a full control by re-excitation from traps, to a small contribution of re-excitation by mobile carriers or other QDs, as low as 5%.