Enhanced Photon Extraction from a Nanowire Quantum Dot Using a Bottom-Up Photonic Shell

TL;DR

This paper presents a bottom-up fabrication method to enhance photon extraction from nanowire quantum dots by adding an oxide shell, resulting in significantly increased collected photoluminescence and emission rate improvements.

Contribution

The study introduces a novel ex situ bottom-up approach to create a photonic shell around nanowire quantum dots, boosting photon extraction efficiency compared to existing top-down methods.

Findings

Fourfold increase in collected photoluminescence

Emission rate enhancement due to light redirection

Simulation predicts 7-fold increase in collected intensity

Abstract

Semiconductor nanowires offer the possibility to grow high-quality quantum-dot heterostructures, and, in particular, CdSe quantum dots inserted in ZnSe nanowires have demonstrated the ability to emit single photons up to room temperature. In this paper, we demonstrate a bottom-up approach to fabricate a photonic fiberlike structure around such nanowire quantum dots by depositing an oxide shell using atomic-layer deposition. Simulations suggest that the intensity collected in our NA = 0.6 microscope objective can be increased by a factor 7 with respect to the bare nanowire case. Combining microphotoluminescence, decay time measurements, and numerical simulations, we obtain a fourfold increase in the collected photoluminescence from the quantum dot. We show that this improvement is due to an increase of the quantum-dot emission rate and a redirection of the emitted light. Our ex situ fabrication technique allows a precise and reproducible fabrication on a large scale. Its improved extraction efficiency is compared to state-of-the-art top-down devices.