Materials Science

Tracking Graphene Growth

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Science  25 Oct 2013:
Vol. 342, Issue 6157, pp. 403
DOI: 10.1126/science.342.6157.403-d

A convenient route for preparing monolayer graphene is via chemical vapor deposition of hydrocarbons onto copper substrates held at elevated temperatures. Kidambi et al. examined how changes in process conditions affect the growth chemistry with several in situ techniques, including x-ray photoelectron spectroscopy (XPS) and environmental scanning electron microscopy (ESEM). They used benzene as the hydrocarbon source (at partial pressures up to ∼4 torr) at substrate temperatures of 900°C. During growth in the absence of air, a shift in the main C1s XPS peak indicated that graphene was coupled to metallic copper. After cooling in vacuum and air exposure, the main carbon feature underwent a shift indicative of decoupling of the graphene from the surface via oxygen intercalation, rather than surface oxidation. Visualization of this decoupling with ESEM revealed an island-growth process proceeding from the edges of the island inward. However, if air was present during growth, there was an increase in the carbon peak associated with carbon deposition at defect sites; surface oxide formed, and roughly half of the graphene present was decoupled from the surface.

Nano Lett. 13, 4769 (2013).

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