The evolution of configuration and final state of graphene on rough iron surface

Molecular dynamics simulations are performed to investigate the evolution of configuration and morphology defects, the final strain and strain induced energy state of graphene on rough iron substrate. A series of randomly rough surfaces are modeled to simulate the real iron surface for the first time. The results show that the formation of morphology defects in graphene are mainly caused by the rapid normal displacement and the following shrinking along lateral directions that are both induced by the strong adhesion between graphene and iron. Fortunately, this strong adhesion cannot lead to global strain in whole graphene layers, i.e., the C–C strain are almost localized around the peaks of the asperities. Thus, the deformation energy (~20 meV/C atom) is mainly induced by bond angle bends and dihedral rotations rather than the expansion or compression of bond length. Through statistical analysis, we further find that the strain and deformation energy are linearly dependent on the substrate roughness. Our findings provide insight into tuning the morphology of graphene and the substrate designing of graphene-based devices. As the photoelectric performance of graphene is largely influenced by strain, our study also provides a guiding direction for evaluating the performance of graphene devices.