Charge transport in disordered graphene-based low dimensional materials

Abstract

Two-dimensional graphene, carbon nanotubes, and graphene nanoribbons represent a novel class of low dimensional materials that could serve as building blocks for future carbon-based nanoelectronics. Although these systems share a similar underlying electronic structure, whose exact details depend on confi nement effects, crucial differences emerge when disorder comes into play. In this review, we consider the transport properties of these materials, with particular emphasis on the case of graphene nanoribbons. After summarizing the electronic and transport properties of defect-free systems, we focus on the effects of a model disorder potential (Anderson-type), and illustrate how transport properties are sensitive to the underlying symmetry. We provide analytical expressions for the elastic mean free path of carbon nanotubes and graphene nanoribbons, and discuss the onset of weak and strong localization regimes, which are genuinely dependent on the transport dimensionality. We also consider the effects of edge disorder and roughness for graphene nanoribbons in relation to their armchair or zigzag orientation.

Edge magnetotransport in graphene: A combined analytical and numerical study

“…In graphene nanoribbons it can be necessary to take into account also the interaction to second and third nearest neighbors [33][34][35]. However, for the graphene stripes studied here, it is sufficient to consider only nearest neighbors, as our main results remain qualitatively unchanged if also second and third nearest neighbors are taken into account.…”

Impact of Vacancies on Diffusive and Pseudodiffusive Electronic Transport in Graphene

“…For the case of the zGNRs (see Figure 7b), a small peak around E = 0 is seen. This is due to the transmission of the electrons through the first (edge) mode of the zigzag system [38], which is also active at low energy in the undoped region. At E = 0 the bands in the zigzag undoped region are almost flat, the density of states is very high and this explains the peak.…”

Charge and Spin Transport in Disordered Graphene-Based Materials

“…The doping of contacts is simulated by adding an onsite energy of -1.5 eV to the corresponding orbitals, which generates a large DOS imbalance between the contacts and the central strip at the Dirac point (E = 0). The zero-temperature conductivity of the graphene strip is then computed as σ(E) = (2e 2 /h)×T (E)×L/W , where T (E) is the transmission coefficient evaluated within the Green's function approach [138,139]. When L ≪ W , low energy transport is dominated by tunneling through the undoped region yielding a universal ballistic value σ(E ≈ 0) ≈ σ min = 4e 2 /πh at the Dirac point for clean strips [123,63,124,138].…”