Effects of polymer residue on the pull-in of suspended graphene

Abstract

Graphene is an ideal candidate for building microelectromechanical system (MEMS) devices because of its extraordinary electronic and mechanical properties. Some research has been done to study the MEMS pull-in phenomenon in suspended graphene, but no one has yet considered the effects of polymer residue. Polymer residue is an inevitable consequence when transferring polycrystalline graphene (PCG) grown using chemical vapor deposition, the most common graphene growth method. Polymer residue is also introduced when using photolithography to build MEMS devices. In this paper, the authors study the effects of polymer residue on the pull-in of suspended PCG ribbon devices and find that thick polymer residues cause a variation in pull-in voltage. However, after removing most of the polymer residue using a more abrasive chloroform treatment, the authors find that the graphene structure is no longer able to suspend itself as the graphene-substrate interaction energy becomes greater than the strain energy needed to conform graphene to the substrate. Therefore, polymer residue is found to cause variation in the pull-in voltage but is also found to help in graphene’s suspension at high length to displacement ratios.