Strain dependence of photoluminescence and circular dichroism in transition metal dichalcogenides: a k.p analysis

Shahnaz Aas, Ceyhun Bulutay

Published 2018-07-23Version 1

Within a two-band $k\cdot p$ method we analyze different types of strain for the $K$ valley bandedge optical characteristics of a freestanding monolayer MoS$_2$, MoSe$_2$, WS$_2$ and WSe$_2$. Wide range of available strained-sample photoluminescence data can be reasonably reproduced by this simple bandstructure and accounting for excitons at a variational level. Accordingly, the shear strain only leads to shifting of the band extremum wavevector without a change in the bandgap or the effective masses. Furthermore, under the stress loading of flexible substrates the presence of Poisson's effect or lack of it are examined individually for the reported measurements. Finally, we predict that circular polarization selectivity for energies above the direct transition onset deteriorates/improves by tensile/compressive strain.