Effect of uniaxial strain on low frequency Raman modes in few layers molybdenum disulfide

The effect of uniaxial tensile strain on the shear mode (C mode) and layer breathing mode (LB mode) of few layers MoS2 were studied. The C mode is doubly degenerated into two sub-peaks as applied strain increases. No measurable Raman shift for the LB mode is observed, while its Raman intensity decreases gradually as the strain increases. In addition, the C and LB modes exhibit distinguished thickness dependence. The C mode shows a clear blueshift as the strain increases, while the LB mode is softened in the process. Moreover, the evolution of C mode with thickness follows an enhanced linear-chain model plus a linear component very well. It implies that the C mode is a better thickness navigator as compared to the L mode.