Ultralong Natural Graphene Nanoribbons and Their Electrical Conductivity

A study was conducted to demonstrate a method for investigating ultralong graphene nanoribbons (GNR) and their electrical conductivity. The method investigated graphene-flake deposition based on silicone stamps using optical and atomic force microscopy (AFM) to characterize the flakes. It was demonstrated that ultralong GNRs with a minimum width below 20nm were electrically characterized by conductance AFM. It was observed that additional properties emerged in the graphene when it was reduced to a long nanometer-wide ribbon. It was also demonstrated that crystallographic orientation played a key role in determining the electrical properties of GNRs. A more detailed inspection near these ribbons using AFM and scanning electron microscopy revealed that they were composed of narrower nanoribbons whose widths ranged between ≈20-120 nm. The use of AFM allowed to characterize the thickness of these flakes and nanoribbons that were thin as a single monolayer.