Semiconductor-metal nanoparticle molecules: hybrid excitons and non-linear Fano effect

TL;DR

This paper theoretically investigates hybrid semiconductor-metal nanoparticle molecules, revealing strong exciton-plasmon coupling and a novel non-linear Fano effect that alters their optical absorption properties.

Contribution

It introduces a theoretical analysis of optical properties in hybrid semiconductor-metal nanoparticles, highlighting a new non-linear Fano effect distinct from traditional linear Fano resonances.

Findings

Exciton peaks are broadened and shifted at low light intensities.

High light intensities induce a strongly asymmetric absorption spectrum.

The asymmetric shape results from coherent Coulomb interactions, indicating a non-linear Fano effect.

Abstract

Modern nanotechnology opens the possibility of combining nanocrystals of various materials with very different characteristics in one superstructure. The resultant superstructure may provide new physical properties not encountered in homogeneous systems. Here we study theoretically the optical properties of hybrid molecules composed of semiconductor and metal nanoparticles. Excitons and plasmons in such a hybrid molecule become strongly coupled and demonstrate novel properties. At low incident light intensity, the exciton peak in the absorption spectrum is broadened and shifted due to incoherent and coherent interactions between metal and semiconductor nanoparticles. At high light intensity, the absorption spectrum demonstrates a surprising, strongly asymmetric shape. This shape originates from the coherent inter-nanoparticle Coulomb interaction and can be viewed as a non-linear Fano effect which is quite different from the usual linear Fano resonance.