Mechanical properties of a silicon nanofilm covered with defective graphene

Molecular dynamics simulations are used to investigate the mechanical properties of a silicon nanofilm covered with a defective graphene. Our results show that graphene not only enhances the mechanical properties of a silicon nanofilm but also unifies the mechanical properties of the ultrathin silicon nanofilms among different crystal orientations. The Young's modulus and critical stress of the silicon nanofilm along four crystal orientations covered with graphene decrease as the thickness of the silicon nanofilm increases. In addition, we study the effects of monoatomic vacancies and Stone-Wales (SW) defects with various concentrations on the mechanical properties of a silicon nanofilm covered with defective graphene. The results show that Young's modulus reduces linearly for monoatomic vacancies and a relatively smaller dependence is observed on SW defects, while the critical stress is more sensitive to the presence of both types of defects. The results in this paper demonstrate the significance of graphene in enhancing the mechanical properties of the silicon nanofilm. (C) 2013 Elsevier B.V. All rights reserved.