Systematic Investigation of the Intrinsic Channel Properties and Contact Resistance of Monolayer and Multilayer Graphene Field-Effect Transistor

The intrinsic channel properties of monolayer and multilayer graphene were systematically investigated as a function of layer number by the exclusion of contact resistance using four-probe measurements. We show that the continuous change in normalized sheet resistivity from graphite to a bilayer graphene is governed by one unique property, i.e., the band overlap, which markedly increases from 1 meV for a bilayer graphene to 11 meV for eight layers and eventually reaches 40 meV for graphite. The monolayer graphene, however, showed a deviation in temperature dependence due to a peculiar linear dispersion. Additionally, contact resistivity was extracted for the case of typical Cr/Au electrodes. The observed high contact resistivity, which varies by three orders of magnitude (from ~103 to 106 Ω µm), might significantly mask the outstanding performance of the monolayer graphene channel, suggesting its importance in future research.