Influence of lattice vibrations on luminescence and transfer of excitons in WS2 monolayer semiconductors. (21st October 2016)

• Record Type: Journal Article
• Authors: Wang, X H; Su, Z C; Ning, J Q; Wang, M Z; Xu, S J; Han, S; Jia, F; Zhu, D L; Lu, Y M
• Is Part Of: Journal of physics. Volume 49:Number 46(2016)
• Publication Date: 2016-10-21
• Subjects: tungsten sulfide -- 2D material -- photoluminescence -- exciton–phonon coupling; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/49/46/465101
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Monolayers of transition metal dichalcogenides (TMDs) have been recently demonstrated to be a new family of direct bandgap semiconductors exhibiting extraordinary excitonic effects and high-efficiency luminescence. Here we present a micro-photoluminescence (PL) study on temperature dependent luminescence of excitons from an exfoliated WS2 monolayer. It is found that lattice vibrations (i.e. phonons) have a profound influence on the excitonic luminescence of the WS2 monolayer in several aspects including the spectral peak shift, lineshape broadening, transfer, and even formation entropy of excitons. Our study not only leads to the determination of the fundamental excitonic bandgap: E g = 2.061 eV at T = 0 K, but also reveals that 120 K is a 'turning' temperature for the competition and formation entropy of free excitons and defect-bound excitons in the studied 2D WS2 crystals.