Raman-scattering measurements and first-principles calculations of strain-induced phonon shifts in monolayer MoS2

The effect of strain on the phonon modes of monolayer and few-layer MoS2 has been investigated by observing the strain-induced shifts of the Raman-active modes. Uniaxial strain was applied to a sample of thin-layer MoS2 sandwiched between two layers of optically transparent polymer. The resulting band shifts of the E-2g(1) (similar to 385.3 cm(-1)) and A(1g) (similar to 402.4 cm(-1)) Raman modes were found to be small but observable. First-principles plane-wave calculations based on density functional perturbation theory were used to determine the Gruneisen parameters for the E-1g, E-2g(1), A(1g), and A(2u) modes and predict the experimentally observed band shifts for the monolayer material. The polymer-MoS2 interface is found to remain intact through several strain cycles. As an emerging 2D material with potential in future nanoelectronics, these results have important consequences for the incorporation of thin-layer MoS2 into devices. DOI: 10.1103/PhysRevB.87.081307