Phase transition in bilayer MoS 2 under tensile loading: A molecular dynamics study.

Molybdenum disulfide (MoS 2 ), especially single layer MoS 2 , have been experimentally and computationally discovered to exist in several different polymorphs, which exhibit various electronic and mechanical properties. The morphology of MoS 2 can be tuned through strain engineering. Molecular dynamics (MD) simulations are conducted to systematically study the phase transition of single layer MoS 2 and bilayer MoS 2 under the uniaxial tensile condition at room temperature. The roles of edge and S-line vacancy are investigated. Phase transitions are always triggered near the edge and vacancy sites. The initiation of metastable T" phase can release the tensile stress in the lattice, followed by I4/mmm phase initiation, regardless of the edge conditions. The growth of I4/mmm phase can cause the local buckling of the MoS 2 plane. With a tilted S-line vacancy, I4/mmm phase is first initiated to reduce the local shear stress accumulated near the vacancy line. Overall, the phase transition mechanism of single layer and bilayer MoS 2 under the tensile loading is provided, which guides the future strain engineering of MoS 2 in nanoelectronics applications.