Unveiling conducting pathways embedded in strongly disordered graphene

Abstract

Graphene shows very different electrical properties under the influence of electrical environments. For example, pristine graphene can show either insulating or normally metallic behavior when supported by different substrates. Here we study charge transport in disordered graphene grown by chemical vapor deposition with varying channel widths. We demonstrate that at high temperatures homogeneous hopping governs the electrical characteristics, whereas at low enough temperatures where charge hopping is frozen out carriers through the embedded weakly disordered conducting pathways contribute a finite conductance instead of being strongly insulating. Our work not only reveals their inhomogeneous features but also provides a new approach for characterizing the surface disorder in large-area graphene systems.

Landau-level mixing, floating-up extended states, and scaling behavior in a GaAs-based two-dimensional electron system containing self-assembled InAs dots

“…While the flow lines show the scaling behavior, the universality in κ is not found, showing that surviving scaling features can still be observed when the universal scaling is invalid. We plan to extend this concept to the fractional QH regime [43] and other disordered systems [44][45][46][47][48].…”

A Self-Assembled Graphene Ribbon Device on SiC

“…The presence of PMMA and other organic residues may significantly degrade the quality of bulk graphene and the smoothness of graphene edges and introduce carrier density inhomogeneity, resulting in unintentional variable range hopping (VRH) transport in graphene-based devices. 10,11 Here we report self-assembled epitaxial graphene ribbons on SiC prepared by a controlled high-temperature sublimation technique, similar to the approach of growing large-area monolayer graphene on SiC. 12 In our work, graphene ribbons, whose widths are a couple of hundred nanometers, can be readily and efficiently located (10 min over an area of 360 μm × 360 μm) by confocal laser scanning microscopy (CLSM).…”

“…It is known that graphene could be doped by PMMA and its residues, which are difficult to be fully removed after e-beam lithography and subsequent processes. The presence of PMMA and other organic residues may significantly degrade the quality of bulk graphene and the smoothness of graphene edges and introduce carrier density inhomogeneity, resulting in unintentional variable range hopping (VRH) transport in graphene-based devices. , …”