Investigation of magnetoconductivity and surface properties of exfoliated and epitaxially grown graphene samples

In this study, the properties of the surface and magnetoconductivity of exfoliated and epitaxially grown graphene samples were investigated. The properties of the surface of graphene samples were investigated by using optical microscope, AFM, and SEM. The Raman spectrum was measured to determine the number of layers which the epitaxial graphene samples have. The graphene devices were fabricated by using optical and e-beam lithography methods for Hall effect and I-V measurements. I-V characteristics of the exfoliated and epitaxially grown graphene samples were measured. To investigate the effect of light on the properties of magnetoconductivity of graphene, under of a fixed magnetic field, Hall effect measurements were carried out under dark and then illumination conditions at the 25-300 K temperature range. To investigate the effects of helium gas and water on Hall measurements of epitaxial graphene, under of a fixed magnetic field, Hall effect measurements were carried out at the 30-300 K temperature range. To better understand the interaction of helium with graphene, DFT calculations were performed.Key Words : Graphene, Lithography, Raman, AFM, SEM, Hall effect