Strain tuning of optical emission energy and polarization in monolayer and bilayer MoS 2

C. Zhu (1) , Gang Wang (1) , B. Liu (1) , Xavier Marie (2) , X. Qiao (3) , X. Zhang (3) , X. Wu (1) , H. Fan (1) , H. Tan (3) , Thierry Amand (2) , B. Urbaszek (2)

1 Beijing National Laboratory for Condensed Matter Physics
2 LPCNO - Laboratoire de physique et chimie des nano-objets
3 State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences

We use micro-Raman and photoluminescence (PL) spectroscopy at 300 K to investigate the influence of uniaxial tensile strain on the vibrational and optoelectronic properties of monolayer and bilayer MoS2 on a flexible substrate. The initially degenerate E′ monolayer Raman mode is split into a doublet as a direct consequence of the strain applied to MoS2 through Van der Waals coupling at the sample-substrate interface. We observe a strong shift of the direct band gap of 48 meV/(% of strain) for the monolayer and 46 meV/% for the bilayer, whose indirect gap shifts by 86 meV/%. We find a strong decrease of the PL polarization linked to optical valley initialization for both monolayer and bilayer samples, indicating that scattering to the spin-degenerate Γ valley plays a key role.

Domaines: Optique [physics.optics]

C. Zhu, Gang Wang, B. Liu, Xavier Marie, X. Qiao, et al.. Strain tuning of optical emission energy and polarization in monolayer and bilayer MoS 2. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2013, 88 (12). ⟨hal-02050742⟩