Programme

P.80 -- Poster, VCTP-45

Date: Wednesday, 14 October 2020

Time: 08:30 - 10:00

Online presentation

Exciton Creation and Annihilation Mechanism in Monolayer WSe2 under Tensile and Compressive Strains

Tran Thi Nhan (1), Tran Quang Huy (2), Luong Thi Theu (2), Van An Dinh (3)

(1) Hanoi University of Industry, 298 Cau Dien, Hanoi, Vietnam; (2) Faculty of Physics, Hanoi Pedagogical University 2, Hanoi, Vietnam; (3) Nanotechnology Program, VNU Vietnam Japan University, Luu Huu Phuoc, My Dinh I, Hanoi, Vietnam

We present a density functional study on the effect of tensile and compresive strains on the electronic structure and the creation/annihilation mechanism of excitons in monolayer WSe2 using the van der Waals functional optB88-vdW with talking the spin-orbit coupling effect into account. Based on the partial projected band structure, the spin splitting of the band edges is carefully interpreted. Moreover, excitons arisen from the five valleys around the Fermi level are specifically indicated. The calculation gives a good agreement between the electronic structure and emission spectra related to A and B excitons. Since the deformation of orbital state dz2 is sensitive to strain, the dispersion of the bands predominately occupied by dz2 at the band edges strongly changes and the band gap notably reduces when strain is applied. Furthermore, the excitons at K valleys are remarkably stabilized while the excitonic annihilation at the four remaining valleys occurs as applying tensile strain. Inversely, excitons at K and Q valleys might disappeared and the momentum excitons are strongly stabilized under compression. Our research suggests a guide to manipulate several kinds of excitons in TDM materials.

Presenter: Tran Thi Nhan

Presentation file: