Date on Master's Thesis/Doctoral Dissertation
Department of Physics
Sumanasekera, Gamini U.
Graphene; Hydrogen plasma; Scaling function
Energy storage--Research; Graphene; Scaling laws (Statistical physics)
Monolayer Graphene synthesized by chemical vapor deposition was subjected to controlled and sequential hydrogenation using RF plasma while monitoring its electrical properties in-situ. Low temperature transport properties were measured for each sample and correlated with ex-situ Raman scattering and X-ray photoemission characteristics. The dominant transport mechanism for weak hydrogenation was found to be electron diffusion and low temperature transport for strong hydrogenation is governed by variable range hopping. This investigation of transport properties of hydrogenated graphene supports to develop the universal scaling functions for metallic and insulating graphene by identifying the critical hydrogen concentration. A clear transition from Weak to Strong localization was identified by the pronounced negative magneto resistance. Variable temperature measurements done on sequentially fluorinated graphene too demonstrated a transition from metallic to semiconductor behavior. The temperature dependence of resistance supports the emergence of a bandgap in the fluorinated graphene films. Controllably fluorinated carbon nanotubes showed promise for high capacity primary and secondary battery performances.
Atapattu Mudiyaneselage, Ruwantha Jayasingha 1980-, "In-situ monitoring of transport properties of graphene during plasma functionalization and it's applications in energy storage." (2013). Electronic Theses and Dissertations. Paper 55.