Graphene etchant

Graphene etchant

Material Name: Graphene
Recipe No.: 12057
Primary Chemical Element in Material: C
Sample Type: Thin film
Uses: Nanostructure
Etchant Name: Graphene etchant
Type (Macro/Micro): Micro
Etching Method: Plasma etching
Etchant (Electrolyte) Composition: Oxygen plasma
Procedure (Condition): Graphene devices are exposed cumulatively to short pulses (~1/2 seconds) of oxygen plasma in a microwave plasma system (Plasma-Preen II-382) operating at 100 W. A constant flow of O2 is pumped through the sample space, and the gas is excited by microwave (manually pulsed on and off). The microwave generates an ionized oxygen plasma, which generates etched holes (observable by AFM similar as previously reported) in graphene. The microwave excited plasma pulses are applied to the samples cumulatively, and field-effect and Raman measurements are performed as soon as possible (~5 min) in ambient atmosphere and temperature after each pulse. The magneto-transport data are taken using a He3 superconducting magnet probe several days after plasma exposure.
Note: Graphene samples are fabricated by micromechanical exfoliation of highly ordered pyrolytic graphite (HOPG, “ZYA” grade, Momentive Performance Materials) onto a p-doped Si wafer with 300 nm of SiO2. Single-layer graphene flakes, typically around 100 mm2 in size, are identified using color contrast with an optical microscope and then confirmed with Raman spectroscopy (using a 532 nm excitation laser). Graphene field-effect devices are fabricated using electron-beam lithography. The electrical contacts (5 nm-thick chromium and 35 nm-thick gold) are fabricated by electron-beam evaporation.
Reference: Isaac Childres, et al., Effect of oxygen plasma etching on graphene studied with Raman spectroscopy and electronic transport, New Journal of Physics, Volume 13, February 2011, pp. 1-12.