| The electronic properties of metal-decorated graphene were systematically investigated. Before decoration performed to the pristine graphene, the quality and homogeneity of pristine graphene devices had been verified through their ambipolar field effect and magneto-transport. By decorating single-layer graphene with noble metal (Ag, Au and Pt) clusters, we investigated experimentally the influence of strong random scatterings on graphene transport and electron localization phenomena. As evidenced by micro Raman scattering, there is a strong interaction between the metal clusters and graphene. Such a strong interaction was the consequence of plasma-assisted decoration of the graphene by the metal clusters. A large negative magnetoresistance (MR) effect (up to 80 % at 12 T) was observed and fitted using different models. The structure, size and area density of metal clusters were characterized by scanning tunneling microscopy and transmission electron microscopy. The samples with a high concentration of scattering centers behaved as insulators at low temperatures and showed strong localization effects. Their temperature-dependent conductance was in accordance with the two-dimensional variable-range hopping mechanism. The localization lengths and density of states were estimated and discussed.;High quality top-gate pristine graphene devices were fabricated using ultra-thin Yttrium oxide as dielectric layer. Quantum capacitance of pristine graphene were extracted, which agreed with the theoretical prediction well. The measured quantum capacitance of silver-decorated graphene at 300K decreased as the decoration increased. And it also decreased as the temperature decreased. In magnetic field up to 9T, the measured quantum capacitance increased by at least 10%. A model based on the fluctuation of local density of states (FLDOS) due to the restored localization effect in silver-decorated graphene was proposed, which succeeded in interpreting the measured quantum qualitatively. |
