2023, Strain-Tunable Valley Polarization and Localized Excitons in Monolayer WSe2, Optics Letters.

2023, Strain-Tunable Valley Polarization and Localized Excitons in Monolayer WSe₂, Optics Letters

Abstract:

Monolayer transition metal dichalcogenides (TMDs) have a crystalline structure with broken spatial inversion symmetry, making them promising candidates for valleytronic applications. However, the degree of valley polarization is usually not high due to the presence of intervalley scattering. Here, we utilize the nanoindentation technique to fabricate strained structures of WSe₂ on Au arrays, thus demonstrating the generation and detection of strained localized excitons in monolayer WSe₂. Enhanced emission of strain-localized excitons was observed as two sharp photoluminescence (PL) peaks measured using low-temperature PL spectroscopy. We attribute these emerging sharp peaks to excitons trapped in potential wells formed by local strains. Furthermore, the valley polarization of monolayer WSe₂ is modulated by plasmons and magnetic field, and the valley polarization of strained localized excitons is increased, with a high value of up to approximately 79.6%. Our results show that strain-tunable valley polarization and localized excitons can be realized in WSe₂ monolayers, which may be useful for valleytronic applications.

Keywords: Transition metal dichalcogenides;Valley polarization;Strained localized excitons.

Link: https://opg.optica.org/ol/abstract.cfm?uri=ol-48-9-2393

Strain-tunable valley polarization and localized excitons in monolayer WSe2pdf.pdf