Adhesion between nanoscale asperities and graphene: A study of two- dimensional atomic membranes using atomic force microscopy (AFM)

摘要

In this work, we studied the adhesion characteristics between exfoliated graphene and nanoscale single asperity tips using AFM. Force-distance spectroscopy showed that the pull-off force between graphene and the AFM tip did not have an appreciable dependence on the number of layers, consistent with FEM analysis. However, our results obtained using a modified FD spectroscopy, such that the pull-off force was measured directly after prolonged sliding, demonstrated that the graphene adhesion has a sliding-history dependence, where the pull-off force of the first FD test immediately after sliding is at least 10% greater than those measured afterward. This observation suggests that the previously-proposed puckering effect [7] can be induced by sliding the tip along the graphene, which in turn affects the adhesiveness of the graphene. Lastly, the effect of sliding-history on the pull-off force is observed frequently for graphene samples having up to 5 layers, and occasionally with bulk graphite. In these cases, we hypothesize that local delamination of topmost graphene layer results in the increased pull-off force.