Conductivity landscape of highly oriented pyrolytic graphite surfaces containing ribbons and edges

Abstract

We present an extensive study on electrical spectroscopy of graphene ribbons and edges of highly oriented pyrolytic graphite (HOPG) using atomic force microscope (AFM). We have addressed in the present study two main issues, (1) How does the electrical property of the graphite (graphene) sheet change when the graphite layer is displaced by shear forces? and (2) How does the electrical property of the graphite sheet change across a step edge? While addressing these two issues we observed, (1) variation of conductance among the graphite ribbons on the surface of HOPG. The top layer always exhibits more conductance than the lower layers, (2) two different monolayer ribbons on the same sheet of graphite shows different conductance, (3) certain ribbon/sheet edges show sharp rise in current, (4) certain ribbons/sheets on the same edge shows both presence and absense of the sharp rise in the current, (5) some lower layers at the interface near a step edge shows a strange dip in the current/conductance (depletion of charge). We discuss possible reasons for such rich conducting landscape on the surface of graphite.

Charge transport in disordered graphene-based low dimensional materials

“…In the literature, the edges of graphene sheets from highly oriented pyrolitic graphite have been directly investigated by scanning tunneling microscopy (STM) in association with scanning tunneling spectroscopy (STS) [129 132] and by direct contact atomic force microscopy (AFM) [133,134]. Micro-Raman spectroscopy has also proved to be a valuable tool for studying the armchair or zigzag orientation of the ribbon edges locally [135].…”

Versatile Polymer-Free Graphene Transfer Method and Applications

“…40,41 As shown in Figure 3e, the surface presents several graphitic planes that show distinct electrical conductivity, in agreement with the behavior previously reported employing metal-coated AFM probes for its characterization. [40][41][42][43] We found that a single tip could be used for more than 50 hours for conductive AFM measurements without noticeable deterioration in performance (a total of > 50 images, each of a 5 µm × 5 µm area). Our transfer method brings to the fore a quick and easy approach for making these tips.…”

Terahertz generation from graphite

“…Graphite mainly exists in hexagonal form, but the rhombohedral form can also exist together with the hexagonal structure [4]. Stacking faults in the crystal can act as breaks in the conduction paths along the c-axis direction, which can lead to accumulation of charges [24,25]. These accumulated charges can lead to built-in electric potentials in the crystal.…”