Atomic level cleaning of poly-methyl-methacrylate residues from the graphene surface using radiolized water at high temperatures

Abstract

Large-scale application of graphene requires its clean transfer from thin metal films, where it is grown via chemical vapor deposition (CVD), to any other substrates of interest. All the existing transfer methodologies, however, leave residues at different degrees on graphene surfaces and can only provide atomically clean graphene surfaces in areas as large as ∼10−4 μm2. Here, we transfer CVD-grown graphene using Poly-methyl-methacrylate (PMMA) and present a method that can atomically clean the PMMA residues from a larger surface area of graphene using radiolized water obtained via electron-water interaction at high temperatures. The cleaning process was monitored in-situ using an environmental-mode transmission electron microscopy and electron energy loss spectroscopy. These showed the effectiveness of PMMA removal over areas as large as ∼0.02 μm2, whose size was only limited by the size of the electron beam and the presence of inorganic residues after the transfer process. By overcoming these limitations, we may achieve atomically clean graphene transfer to even larger areas—enabling more challenging device applications.