Tailoring graphene-based nano-devices

Graphene, the purely two-dimensional form of carbon, is a promising candidate for novel electronic devices compatible with the currently dominating CMOS technology. A first step on this long road consists in the control of its structural and electronic properties on a nano-meter scale. For this we use an atomic force microscope (AFM) to nano-manipulate graphene films. In particular, we employ local anodic oxidation of graphene (Fig. 1a) where applying a voltage between tip and substrate in a humid environment causes the graphene to oxidize into a variety of carbon-based oxides and acids. These products will then escape from the surface, thereby effectively cutting out a part of the graphene sheet underneath the tip (Fig. 1b). With an in-situ monitoring of the device resistance across the oxidation path (Fig 1d.) this process can be controlled on a nanoscopic length scale. Line-widths of less than 30 nm are easily achievable (Fig. 1c). These proof-of-principle experiments on AFM lithography on graphene pave the way to an extremely useful and simple technique for the desktop fabrication of graphene-based devices.

Figure: Local anodic oxidation with an AFM. (a) Artistic impression of the oxidation procedure: The AFM-tip oxidizes the graphene, in the presence of a water layer, into carbon-based oxides that escape from the surface. (b) AFM micrograph of an oxidized groove into a graphene ribbon. (c) Cross-section of the micrograph along the green line, showing the oxidized trench. (d) The resistance of the ribbon, monitor-red during oxidation, increases dramatically as it is oxidized in two pieces.

This work was published in:

A.J.M. Giesbers, U. Zeitler, S. Neubeck, F. Freitag, K.S. Novoselov, and J.C. Maan,
Nanolithography and manipulation of graphene using an atomic force microscope,
Solid State Communications 147, 366-369 (2008).