Two very important articles have been issued last month reporting new insights into graphene properties.
The first paper I discuss here has been published on Nature Materials by authors from the Rensselaer Polytechnic Institute and Rice University. It has been demonstrated that a metal (copper, gold and silicon too) coated with one graphene-layer deposited above does not change the wetting behaviour of surfaces. This fact does mean that a hydrophobe metal with a graphene coating remains a hydrophobe metal and, in a similar way, a hydrophile metal after graphene coating is still hydrophile. At the same time it has been demonstrated that the metal is protected against oxydation without disrupting the intrinsic wettability of the surface. Of course, with increasing number of graphene layers, the contact angle of water gradually recovers the bulk graphite value. Therefore, it is said that one graphene layer is conductive and transparent to water, while more than one graphene layers are less transparent or not transparent to water.
The other paper has been issued on Science and the authors are from the research team of Geim and Novoselov (the University of Manchester’s Nobel winners) . They claim to have overcome the difficulties met in substituting silicon with graphene in field effect transistors, due to the difference between the two materials: silicon is a semiconductor ad has an energy gap; graphene is a semi-metal, instead, and is gapless. They exploited the low density of states in graphene and used atomically thin boron nitride or molybdenum disulfide acting as a vertical transport barrier. They demonstrated room temperature switching ratios of ≈50 and ≈10,000 respectively. The authors claim that the devices have potential applications for high-frequency operation and that large-scale integration is also possible.
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