title: Clean transfer of graphene for isolation and suspension.
abstract: Fabrication of large-area clean graphene sheets is the first step toward the development of high-performance applications in surface chemistry and biotechnology as well as in high-mobility electronics. Here we demonstrate the clean transfer of graphene grown by chemical vapor deposition on Cu foil, with surface cleanness defined by transmission electron microscopy (TEM) in combination with Raman scattering on the same position of suspended graphene sheets. For clean graphene, the Raman spectra exhibit distinctive features that can explicitly discriminate from that of graphene covered with a thin layer of amorphous carbon such as residual poly(methyl methacrylate) (PMMA). By applying this technique to graphene sheets with various degrees of surface cleanness, we show that the quantitative characterization of the thickness of surface contaminants is possible based on multiple reflections and interference of light in samples.
authors.affiliation: Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Yung-Chang
authors.initials: YC
authors.lastname: Lin
authors.forename: Chuanhong
authors.initials: C
authors.lastname: Jin
authors.forename: Jung-Chi
authors.initials: JC
authors.lastname: Lee
authors.forename: Shou-Feng
authors.initials: SF
authors.lastname: Jen
authors.forename: Kazu
authors.initials: K
authors.lastname: Suenaga
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Chiu
mesh_terms: D003460:Crystallization / Q000379:methods*; D006108:Graphite / Q000737:chemistry* / Q000302:isolation & purification*; D008567:Membranes, Artificial; D049329:Nanostructures / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D013535:Suspensions
chemical_list: D008567:Membranes, Artificial; D013535:Suspensions; D006108:Graphite