Low Pressure Plasma Cleaning and Doping of CVD Graphene

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Effective patterning and cleaning of graphene by plasma etching and block copolymer lithography for nanoribbons fabrication

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Dry efficient cleaning of poly-methyl-methacrylate residues from graphene with high-density H-2 and H-2-N-2 plasmas

International audienceGraphene is the first engineering electronic material, which is purely two-dimensional: it consists of two exposed sp(2)-hybridized carbon surfaces and has no bulk. Therefore, surface effects such as contamination by adsorbed polymer residues have a critical influence on its electrical properties and can drastically hamper its widespread use in devices fabrication. These contaminants, originating from mandatory technological processes of graphene synthesis and transfer, also impact fundamental studies of the electronic and structural properties at the atomic scale. Therefore, graphene-based technology and research requires "soft" and selective surface cleaning techniques dedicated to limit or to suppress this surface contamination. Here, we show that a high-density H-2 and H-2-N-2 plasmas can be used to selectively remove polymeric residues from monolayer graphene without any damage on the graphene surface. The efficiency of this dry-cleaning process is evidenced unambiguously by a set of spectroscopic and microscopic methods, providing unprecedented insights on the cleaning mechanisms and highlighting the role of specific poly-methyl-methacrylate residues at the graphene interface. The plasma is shown to perform much better cleaning than solvents and has the advantage to be an industrially mature technology adapted to large area substrates. The process is transferable to other kinds of two-dimensional material and heterostructures. (C) 2015 AIP Publishing LLC

Photoemission investigation of the graphene surface cleaning by hydrogen/nitrogen plasma

International audienceIt is known that graphene surface contaminations by residues affect drastically its intrinsic properties and cannot be avoided when chemical vapor deposited (CVD) graphene is transferred on other substrates. In this work, we investigate by X‐ray photoelectron spectroscopy and work function measurements using X‐ray photoemission electron microscopy the capabilities of high‐density plasmas to clean graphene. The evolution of different chemical species at surface is monitored as a function of plasma exposure. H2 plasmas are shown to clean efficiently PMMA residues from CVD graphene on Cu. However, when the same plasma is used on graphene transferred on SiO2/Si substrate a liftoff of the graphene layer is observed before the end of cleaning procedure. These results are discussed in terms of H+ penetration through graphene and H2 formation between the SiO2 substrate and graphene. Using Cl‐based chemistries, we found that the plasma is able to etch polymeric contamination at the graphene surface. It is also found that the plasma induces spreading of the Si nanoparticle contamination that hampers the cleaning process

Graphene structuration by self-assembly of block copolymers

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XPS investigations of graphene surface cleaning using H 2 - and Cl 2 -based inductively coupled plasma

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H2 Plasma Interaction with CVD Graphene

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Fabrication of high quality graphene nanoribbons on large surfaces by block copolymer lithography

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