Article: Neutral and charged excitons in tungsten dichalcogenides monolayer Journal: International Journal of Nanotechnology (IJNT) 2016 Vol.13 No.8/9 pp.619 - 626 Abstract: Monolayer transition metal dichalcogenides (TMDs) represent an alternative group of two dimensional (2D) layered materials that differ from the semimetallic character of graphene. They have aroused great attention owing to their peculiar physical properties, in particular the strong electron-hole interaction. Largely motivated by enhancement of the binding energies of exciton and trion in TMDs, we present a theoretical model to describe the formation of trion in monolayer WS2 and WSe2, obtained by exfoliating n-type bulk crystals. We show that the binding energies of excitonic states deviate strongly from the standard 2D Wannier Mott model owing to the correlations with the surrounding dielectric environment. Therefore, using a non-local dielectric screening potential, exciton and trion energies are shown to be in excellent agreement with photoluminescence (PL) measurements. According to the mass action law, we calculate the dependence of the intensity of neutral and charged excitons on temperature, pumping and injection electron. Inderscience Publishers - linking academia, business and industry through research

Title: Neutral and charged excitons in tungsten dichalcogenides monolayer

Authors: A. Hichri; S. Jaziri

Addresses: Département de Physique, Laboratoire de Physique des Matériaux, Faculté des Sciences de Bizerte 7021 Jarzouna, Université de Carthage, Tunisia ' Département de Physique, Laboratoire de physique de la matière condensée, Faculté des Sciences de Tunis 2092 El Manar, Université El Manar, Tunisia

Abstract: Monolayer transition metal dichalcogenides (TMDs) represent an alternative group of two dimensional (2D) layered materials that differ from the semimetallic character of graphene. They have aroused great attention owing to their peculiar physical properties, in particular the strong electron-hole interaction. Largely motivated by enhancement of the binding energies of exciton and trion in TMDs, we present a theoretical model to describe the formation of trion in monolayer WS₂ and WSe₂, obtained by exfoliating n-type bulk crystals. We show that the binding energies of excitonic states deviate strongly from the standard 2D Wannier Mott model owing to the correlations with the surrounding dielectric environment. Therefore, using a non-local dielectric screening potential, exciton and trion energies are shown to be in excellent agreement with photoluminescence (PL) measurements. According to the mass action law, we calculate the dependence of the intensity of neutral and charged excitons on temperature, pumping and injection electron.

Keywords: tungsten disulphide; WS2; tungsten diselenide; WSe2; transition metal dichalcogenides; monolayer TMDs; 2D materials; trions; binding energy; dielectric screening; photoluminescence; mass action model; neutral excitons; charged excitons; electron-hole interaction; temperature; pumping; injection electrons; tungsten dichalcogenides.

DOI: 10.1504/IJNT.2016.079664

International Journal of Nanotechnology, 2016 Vol.13 No.8/9, pp.619 - 626

Published online: 07 Oct 2016 *

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Title: Neutral and charged excitons in tungsten dichalcogenides monolayer

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