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Issue 23, 2015
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Excitonic resonances in thin films of WSe2: from monolayer to bulk material

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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.

Graphical abstract: Excitonic resonances in thin films of WSe2: from monolayer to bulk material

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Publication details

The article was received on 09 Mar 2015, accepted on 07 May 2015 and first published on 11 May 2015


Article type: Paper
DOI: 10.1039/C5NR01536G
Nanoscale, 2015,7, 10421-10429

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    Excitonic resonances in thin films of WSe2: from monolayer to bulk material

    A. Arora, M. Koperski, K. Nogajewski, J. Marcus, C. Faugeras and M. Potemski, Nanoscale, 2015, 7, 10421
    DOI: 10.1039/C5NR01536G

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