Dynamic Tunneling Junctions at the Atomic Intersection of Two Twisted Graphene Edges

Abstract

The investigation of the transport properties of single molecules by flowing tunneling currents across extremely narrow gaps is relevant for challenges as diverse as the development of molecular electronics and sequencing of DNA. The achievement of well-defined electrode architectures remains a technical challenge, especially due to the necessity of high precision fabrication processes and the chemical instability of most bulk metals. Here, we illustrate a continuously adjustable tunneling junction between the edges of two twisted graphene sheets. The unique property of the graphene electrodes is that the sheets are rigidly supported all the way to the atomic edge. By analyzing the tunneling current characteristics, we also demonstrate that the spacing across the gap junction can be controllably adjusted. Finally, we demonstrate the transition from the tunneling regime to contact and the formation of an atomic-sized junction between the two edges of graphene.

Inter‐Flake Quantum Transport of Electrons and Holes in Inkjet‐Printed Graphene Devices

“…The current, I , between flakes is assumed to depend exponentially on the distance, d , according to where V is the potential difference between overlapping flakes on adjacent layers, A is the areal overlap of the flakes, α is the tunneling constant, and we offset the distance between flakes, d , by the van der Waals distance, d VdW = 0.335 nm. [ 42,43 ] We note, that the proportionality constant in Equation (1) could be temperature dependent hence representative of hopping transport. Equation (1) is derived using the Landauer–Büttiker formula [ 44 ] with a tunneling probability found via the Wentzel–Kramers–Brillouin (WKB) approximation.…”

Single-molecule quantum-transport phenomena in break junctions

“…Methods have therefore been developed to fabricate MCBJ junctions that can be used to study molecular transport in a solvent by coating the metal electrode with a thin insulating oxide layer 24,25 . In this respect, graphene is an promising electrode option, and the first graphene-based MCBJs have been fabricated 26,27 .…”

Tunneling devices based on graphene/black phosphorus van der Waals heterostructures

“…From this fit, we obtain a distance of 1.12 nm (±8%) and an effective work function j1=2.8 eV (±10%) for 4-layer sample, and 0.98 nm (±8%), j2=2.8 eV (±10%) for 3-layer sample. The work function is significantly lower than the values obtained by Kelvin probe microscopy on the face of Bp sheets (5.35 to 5.42 eV) and graphene sheets (4.45 to 4.8 eV) [27]. Figure 5(d) shows the response time spectrum of the sample.…”