1306.3442 (G. Wang et al.)

Strain tuning of optical emission energy and polarization in monolayer
and bilayer MoS2    [PDF]

G. Wang, C. R. Zhu, B. L. Liu, X. Marie, Q. X. Feng, X. X. Wu, H. Fan, P. H. Tan, T. Amand, B. Urbaszek

We use micro-Raman and photoluminescence (PL) spectroscopy at 300K 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^1_{2g} 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 48meV/(% of strain) for the monolayer and 46meV/% for the bilayer, whose indirect gap shifts by 86meV/%. 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 Gamma valley plays a key role.

View original: http://arxiv.org/abs/1306.3442