In-situ monitoring of transport properties of graphene during plasma functionalization and it\u27s applications in energy storage.

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

Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001) 6 H-SiC

Article discussing research on charge transfer equilibria in ambient-exposed epitaxial graphene on (0001) 6 H-SiC

Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001¯) 6 H-SiC

Article discussing research on charge transfer equilibria in ambient-exposed epitaxial graphene on (0001) 6 H-SiC

Probing Phonons in Nonpolar Semiconducting Nanowires with Raman Spectroscopy

We present recent developments in Raman probe of confined optical and acoustic phonons in nonpolar semiconducting nanowires, with emphasis on Si and Ge. First, a review of the theoretical spatial correlation phenomenological model widely used to explain the downshift and asymmetric broadening to lower energies observed in the Raman profile is given. Second, we discuss the influence of local inhomogeneous laser heating and its interplay with phonon confinement on Si and Ge Raman line shape. Finally, acoustic phonon confinement, its effect on thermal conductivity, and factors that lead to phonon damping are discussed in light of their broad implications on nanodevice fabrication