Related Experiment Video
Updated: Apr 12, 2026

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems
Published on: April 28, 2016
Excitonic resonances in thin films of WSe2: from monolayer to bulk material
Ashish Arora1, Maciej Koperski, Karol Nogajewski
1Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25 rue des Martyrs, 38042 Grenoble, France. ashish.arora@lncmi.cnrs.fr marek.potemski@lncmi.cnrs.fr.
Abstract:
We present optical spectroscopy (photoluminescence and reflectance) studies of thin layers of the transition metal dichalcogenide WSe2, with thickness ranging from mono- to tetra-layer and in the bulk limit. The investigated spectra show the evolution of excitonic resonances as a function of layer thickness, due to changes in the band structure and, importantly, due to modifications of the strength of Coulomb interactions as well. The observed temperature-activated energy shift and broadening of the fundamental direct exciton are well accounted for by standard formalisms used for conventional semiconductors. A large increase of the photoluminescence yield with temperature is observed in a WSe2 monolayer, indicating the existence of competing radiative channels. The observation of absorption-type resonances due to both neutral and charged excitons in the WSe2 monolayer is reported and the effect of the transfer of oscillator strength from charged to neutral excitons upon an increase of temperature is demonstrated.
Related Concept Videos
The de Broglie Wavelength
Energy Bands in Solids
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states...
Fermi Level Dynamics
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Standing Waves in a Cavity
Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
UV–Vis Spectroscopy: Molecular Electronic Transitions

