High-quality PVD graphene growth by fullerene decomposition on Cu foils

Abstract

We present a new protocol to grow large-area, high-quality single-layer graphene on Cu foils at relatively low temperatures. We use C 60 molecules evaporated in ultra high vacuum conditions as carbon source. This clean environment results in a strong reduction of oxygen-containing groups as depicted by X-ray photoelectron spectroscopy (XPS). Unzipping of C 60 is thermally promoted by annealing the substrate at 800ºC during evaporation. The graphene layer extends over areas larger than the Cu crystallite size, although it is changing its orientation with respect to the surface in the wrinkles and grain boundaries, producing a modulated ring in the low energy electron diffraction (LEED) pattern. This protocol is a self-limiting process leading exclusively to one single graphene layer. Raman spectroscopy confirms the high quality of the grown graphene. This layer exhibits an unperturbed Dirac-cone with a clear n-doping of 0.77 eV, which is caused by the interaction between graphene and substrate. Density functional theory (DFT) calculations show that this interaction can be induced by a coupling between graphene and substrate at specific points of the structure leading to a local sp 3 configuration, which also contribute to the D-band in the Raman spectra.

Multifunctional coatings of exfoliated and reassembled graphite on cellulosic substrates

“…This is also in line with the work of many groups that have already opted for making graphene in situ, e.g on copper foils 58. …”

Structural characterization of as-grown and quasi-free standing graphene layers on SiC

“…For a quantitative analysis, XPS C-1s curves were fitted using standard Gaussian-Lorentzian lines and the corresponding integral background. For reproducing the asymmetric line shape of sp 2 carbon a Doniach and Sunjic line shape with an asymmetry parameter of 0.068 was used [23].…”

Oxygen intercalation in PVD graphene grown on copper substrates: A decoupling approach

“…Over last decade, since the discovery of graphene [ 1 ], many methods have been developed for its synthesis and among them chemical vapor deposition (CVD) is the most widely employed [ 2 ]. A variant of this technique where a solid source of carbon is used, physical vapor deposition (PVD), is one of the most appealing protocols [ 3 , 4 ] as it lowers the temperature required during the growth process and results in layers with a low number of structural and chemical defects. Amongst the growth methods that employ solid carbon sources, a novel method using C 60 as precursor molecules under ultra-high vacuum (UHV) conditions has been recently successfully demonstrated.…”

“…Amongst the growth methods that employ solid carbon sources, a novel method using C 60 as precursor molecules under ultra-high vacuum (UHV) conditions has been recently successfully demonstrated. Although proven to be an effective process to obtain complete, high-quality monolayer graphene over polycrystalline copper foils [ 2 , 4 ], the coupling of the graphene layer with the copper is significant. Presently, metal substrates are incompatible with the exploitation of the unique electronic properties of graphene, making transfer protocols to more technological substrates mandatory.…”

“…All of the previous reports on Cu substrates have in common the use of CVD graphene. As already mentioned, the PVD graphene grown using C 60 as a precursor is defect-free and therefore it highly interacts with the Cu substrate [ 4 ]. We show that a controlled oxygen intercalation process structurally and electronically decouples this highly linked interface, making this process favourable as a first stage for transferring graphene onto other surfaces.…”