Quantum dot photoluminescence as a versatile probe to visualize the interaction between plasma and nanoparticles on a surface

TL;DR

This study uses quantum dot photoluminescence to visualize and analyze plasma interactions with nanoparticles on surfaces, revealing charging effects and enabling detailed understanding of plasma-nanoparticle dynamics.

Contribution

It introduces a novel in-situ spectroscopic method to directly observe plasma-induced charging effects on quantum dots at nanometer scales.

Findings

Fast redshift indicates plasma charging of quantum dots.

Distinction between charging effects and thermal/ion effects.

Method enables visualization of plasma-nanoparticle interactions.

Abstract

We experimentally demonstrate that the interaction between plasma and nanometer-sized semiconductor quantum dots (QDs) is directly connected to a change in their photoluminescence (PL) spectrum. This is done by taking in-situ, high resolution, and temporally-resolved spectra of the light emitted by laser-excited QDs on an electrically floating sample exposed to a low pressure argon plasma. Our results show a fast redshift of the PL emission peak indicating the quantum-confined Stark effect due to direct plasma-charging of these nanostructures and the substrate surface, while other plasma-induced (thermal and ion) effects on longer time scales could clearly be distinguished from these charging effects. The presented results and method open up novel pathways to direct visualization and understanding of fundamental plasma-particle interactions on nanometer length scales.