▎ 摘　　要

The optimization of contacts between graphene and metals is important for many optoelectronic applications. In this work, we evaluate the contact resistance and sheet resistance of monolayer and few-layered graphene with different metallizations using the transfer length method (TLM). Graphene was obtained by the chemical vapor deposition technique (CVD-graphene) and transferred onto GaAs and Si/SiO2 substrates. To account for the quality of large-area contacts used in a number of practical applications, a millimeter-wide TLM pattern was used for transport measurements. Different metals-namely, Ag, Pt, Cr, Au, Ni, and Ti-have been tested. The minimal contact resistance R-c obtained in this work is 11.3 k Omega mu m for monolayer CVD-graphene, and 6.3 k Omega mu m for a few-layered graphene. Annealing allows us to decrease the contact resistance R-c and achieve 1.7 k Omega mu m for few-layered graphene on GaAs substrate with Au contacts. The minimal sheet resistance R-sh of few-layered graphene transferred to GaAs and Si/SiO2 substrates are 0.28 k Omega/square and 0.27 kO/square. The R-sh value of monolayer graphene on the GaAs substrate is 8 times higher (2.3 k Omega/square), but it reduces for the monolayer graphene on Si/SiO2 (1.4 k Omega/square). For distances between the contacts below 5 mu m, a considerable reduction in the resistance per unit length was observed, which is explained by the changes in doping level caused by graphene suspension at small distances between contact pads.