Researchers at MIT believe they may have found a way to produce graphene on a large scale.
The process, developed in collaboration with the University of Michigan, involves growing the wonder material directly onto large sheets of glass. Currently, most methods of making graphene first grow the material on a film of metal, such as nickel or copper. It then has to be taken off the metal and placed onto a substrate, such as a silicon wafer or a polymer sheet. This process often damages the graphene and can even contaminate it. Instead, the MIT team decided to use silicon dioxide, a form of glass, as their substrate, with a layer of nickel on top it. Chemical vapor deposition (CVD) was used to deposit the graphene layer on top of the nickel film, which was later peeled away to leave only the graphene on top of the non-metallic substrate. Lead researcher John Hart explained: "This way, there's no need for a separate process to attach the graphene to the intended substrate – whether it's a large plate of glass for a display screen, or a thin, flexible material that could be used as the basis for a lightweight, portable solar cell, for example. "You do the CVD on the substrate, and, using our method, the graphene stays behind." While promising, the work is still in the early stages. Hart cautioned: "We still need to improve the uniformity and the quality of the graphene to make it useful, but the potential is great. "The ability to produce graphene directly on non-metal substrates could be used for large format displays and touchscreens, and for smart windows that have integrated devices like heaters and sensors." If the graphene is synthesised at lower temperatures, Hart believes it could also be used for small scale applications such as integrated circuits on silicon wafers. "This new process is based on an understanding of graphene growth in concert with the mechanics of the nickel film," he concluded. "We've shown this mechanism can work. Now it's a matter of improving the attributes needed to produce a high performance graphene coating."