Scanning Tunneling Spectroscopy of Reduced Graphene Oxide

Graphene is a two dimensional nanomaterial that has attracted worldwide attention since its discovery in 2004, and it has become a hot topic mainly due to its outstanding properties and promising applications. Graphene, a single layer (one-atom thick) two-dimensional (2D) crystal of carbon atoms arranged in a honeycomb lattice, could be isolated from graphite. As for its electric properties, monolayer of graphene is a semi-metal and its charge carriers are Dirac fermions near Dirac point. The electronic structure of a single layer of graphene has a launch point between the conduction and valence bands that are called Dirac point. These unique properties have stimulated the production of graphene and make it suitable for many applications, such as electronic devices, photonic devices, energy storage, sensors, and etc.[1, 2]. One of the low cost way to produce graphene is by chemical exfoliation from graphene oxide. Reducing percent of oxygen reduced graphene oxide (RGO) is accepted.

In spite of the recent interest in graphene, little is known about the atomic structure and electronic properties of RGO, a semiconductor with a tunable band gap from 2 to 0.02 eV depending on its reduction level [3]. A few studies conducted under ambient conditions have been performed to study oxidized graphite [4, 5]. In this work, we report on our efforts to better characterize RGO deposited onto different substrates. In this initial study, both ultra-high vacuum scanning tunneling microscopy and spectroscopy techniques were chosen because they provide reliable topographic and electronic information with atomic scale resolution.

References:

[1] Yi, M., Journal of Materials Chemistry A 2015, 3 (22), 11700-11715.

[2] Eva, Y., Reports on Progress in Physics 2012, 75 (5), 056501.

[3] Shen, Y., Elsevier CARBON 62 (2013) 157 – 164.

[4] Klusek, Z., Appl. Surf. Sci. 108 (1997) 405.

[5] Pandey, D., Surface Science 602 (2008) 1607–1613.