Transport gap engineering by contact geometry in graphene nanoribbons: Experimental and theoretical studies on artificial materials

Abstract

Electron transport in small graphene nanoribbons is studied by microwave emulation experiments and tight-binding calculations. In particular, it is investigated under which conditions a transport gap can be observed. Our experiments provide evidence that armchair ribbons of width $3m+2$ with integer $m$ are metallic and otherwise semiconducting, whereas zigzag ribbons are metallic independent of their width. The contact geometry, defining to which atoms at the ribbon edges the source and drain leads are attached, has strong effects on the transport. If leads are attached only to the inner atoms of zigzag edges, broad transport gaps can be observed in all armchair ribbons as well as in rhomboid-shaped zigzag ribbons. All experimental results agree qualitatively with tight-binding calculations using the nonequilibrium Green's function method.

7 pages, 5 figures, 1 table

References in corpus (14)

• The electronic properties of graphene
• Energy Gaps in Graphene Nanoribbons
• Valley filter and valley valve in graphene
• Electronic States of Graphene Nanoribbons
• Graphene valley filter using a line defect
• Role of Symmetry in the Transport Properties of Graphene Nanoribbons under Bias
• Electronic transport properties of graphene nanoribbons
• Band-Selective Filter in a Zigzag Graphene Nanoribbon
• Effective contact model for transport through weakly-doped graphene
• Transport through normal metal - graphene contacts
• Manipulation of edge states in microwave artificial graphene
• Electron transport through honeycomb lattice ribbons with armchair edges
• Quantum Transport in Graphene Nanoribbons with Realistic Edges
• Contact conductance between graphene and quantum wires

Cited by in corpus (1)

• Frozen Mode Regime in Finite Periodic Structures