Browsing by Author "Dresselhaus, Mildred S."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Ambient-pressure CVD of graphene on low-index Ni surfaces using methane: A combined experimental and first-principles study
    (American Physical Society, 2018-07-23) Mafra, Daniela L.; Olmos-Asar, Jimena A.; Negreiros, Fabio R.; Reina, Alfonso; Kim, Ki Kang; Dresselhaus, Mildred S.; Kong, Jing; Mankey, Gary J.; Araujo, Paulo T.; Massachusetts Institute of Technology (MIT); Universidade Federal do ABC (UFABC); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); National University of Cordoba; Dongguk University; University of Alabama Tuscaloosa; Universidade Federal do Para
    The growth of large area single-layer graphene (1-LG) is studied using ambient pressure chemical vapor deposition on single-crystal Ni(111), Ni(110), and Ni(100). By varying both the furnace temperature in the range of 800-1100 degrees C and the gas flow through the growth chamber, uniform, high-quality 1-LG is obtained for Ni(111) and Ni(110) single crystals and for Ni(100) thin films. Surprisingly, only multilayer graphene growth could be obtained for single-crystal Ni(100). The experimental results are analyzed to determine the optimum combination of temperature and gas flow. Characterization with optical microscopy, Raman spectroscopy, and optical transmission support our findings. Density-functional theory calculations are performed to determine the energy barriers for diffusion, segregation, and adsorption, and model the kinetic pathways for formation of different carbon structures on the low-index surfaces of Ni.
  • Thumbnail Image
    Item
    Direct transfer of graphene onto flexible substrates
    (National Academy of the Sciences, 2013) Martins, Luiz G. P.; Song, Yi; Zeng, Tingying; Dresselhaus, Mildred S.; Kong, Jing; Araujo, Paulo T.; Universidade Federal de Minas Gerais; Massachusetts Institute of Technology (MIT); University of Alabama Tuscaloosa
    In this paper we explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate transfer membrane, such as polymethylmethacrylate, which needs to be removed afterward. Various substrates of general interest in research and industry were studied in this work, including polytetrafluoroethylene filter membranes, PVC, cellulose nitrate/cellulose acetate filter membranes, polycarbonate, paraffin, polyethylene terephthalate, paper, and cloth. By comparing the properties of these substrates, two critical factors to ensure a successful transfer on bare substrates were identified: the substrate's hydrophobicity and good contact between the substrate and graphene. For substrates that do not satisfy those requirements, polymethylmethacrylate can be used as a surface modifier or glue to ensure successful transfer. Our results can be applied to facilitate current processes and open up directions for applications of chemical vapor deposition graphene on flexible substrates. A broad range of applications can be envisioned, including fabrication of graphene devices for opto/organic electronics, graphene membranes for gas/liquid separation, and ubiquitous electronics with graphene.