GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications

TL;DR

This paper presents the growth and optical characterization of GaAs droplet quantum dots with ultra-thin capping layers, highlighting their potential for plasmonic applications due to their stable, bright emission and proximity to the surface.

Contribution

It introduces a novel growth method with an internal thermal heating step to produce GaAs quantum dots with nanometer-thin capping layers and characterizes their optical properties for plasmonic use.

Findings

Quantum dots exhibit stable, bright, near-infrared emission.

The thin capping layer enables proximity to surface for near-field effects.

Optical properties are suitable for plasmonic coupling studies.

Abstract

We report on the growth and optical characterisation of droplet GaAs quantum dots with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the quantum dots obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single quantum dots, at near-infrared wavelengths. Given the quality of their optical properties and the proximity to the surface, such emitters are ideal candidates for the investigation of near field effects, like the coupling to plasmonic modes, in order to strongly control the directionality of the emission and/or the spontaneous emission rate, crucial parameters for quantum photonic applications.