Strain Engineering of 2D Transition Metal Dichalcogenides

The potential of ultrathin molybdenum disulfide (MoS$_{2})$ nanostructures for applications in electronic and optoelectronic devices requires a fundamental understanding of their electronic structure as a function of strain. The strain dependence of the electronic properties of bilayer sheets of 2H-MoS$_{2}$ has already been studied using \textit{ab initio} simulations based on density functional theory (DFT).\footnote{L. Dong \textit{et al. } \textit{Appl. Phys. Lett}. \textbf{104}, 053107 (2014).} In this work, we use CVD grown bilayer MoS$_{2}$ triangles to verify the predicted results, both through optical and electrical measurements as a function of dynamic and static strains. By transferring the MoS$_{2}$ onto a flexible substrate and performing Raman characterization as a function of uniaxial strain, it was observed that while the monolayer MoS$_{2}$ triangles were able to withstand strains of up to 1.2{\%} before slippage, the bilayer triangles slipped at strains less than or equal to 0.5{\%}, suggesting that it is possible the strain is distributed differently in the two layers. With this in mind, we looked at the Raman as a function of strain for vertically grown triangles of MoS$_{2}$ consisting of 1, 2, 3, 4, and \textgreater 4 layers on a single triangle to study the distribution of strain in multilayered 2D materials.