Properties and applications of graphene membranes grown on Co

Graphene grows on cobalt by means of diffusion of carbon atoms during the isothermal stage of exposure to hydrocarbon precursor, followed by precipitation during cooling. This method, largely applied with the nickel catalyst, is known to produce continuous, but not uniform, layers with the concurrent presence of mono- and poly-graphene areas. Many distortions of the Raman signatures can, however, be interpreted as related to strain. A detailed investigation of this effect is provided. The material has better mechanical stability with respect to the Cu-grown graphene and can be easily transferred without the aid of any polymeric support. This makes our graphene particularly suited for the realization of suspended membranes. One possible application of such membranes is the realization of suspended lithographic masks for shadow evaporation. This technique, which is largely used for realizing mesoscopic devices where the quality requirements for the junctions prevent the exposure to ambient air and the occurrence of quantum phenomena requires highly defined structures, can be improved by the use of pure 2-dimensional masks, like those made with graphene. Advantages and differences with respect to the polymers commonly employed are presented and discussed.