Mechanical Impacts of Random Defects in Monolayer MoS2 by Stochastic Finite Element Modeling

Randomly distributed sulfur vacancy defects (V-S) in monolayer molybdenum disulfide (MoS2) are inevitable that affect the mechanical and electronic properties of the two-dimensional material. Conventional first-principles modeling, however, can hardly capture the randomness of such defects, which is anticipated to be closely related to realistic properties. In this work, the impacts of random VS defects have been explored by a large-scale stochastic finite element model based on Monte Carlo sampling. The computation provides probability distributions of the strain energy, sum of squared displacements, and equivalent elastic modulus, which are delicately shaped by the preset V-S concentration. The former two manifest concurrent and evident discrete distribution at low concentrations, but the discreteness smears out at a critical concentration of >3%. Interestingly, the discreteness is absent for the equivalent elastic modulus distribution and only peak shifts occur. Importantly, the elastic properties of MoS2 deteriorate by up to 53.29% with only 5% sulfur vacancies, highlighting the crucial role of defects in mechanical reliability. This work hence provides an essential numerical perspective in understanding the mechanical properties affected by random atomic defects and paves the way for realizing ultrathin nanoelectromechanical systems.