Copper SubstrateÃ¢â‚¬â„¢s Crystal Form Affect Graphene Growth
There is a great hope for a future with graphene based computers, instead of silicon. Graphene, a single atom thick layer of carbon, has many special properties including extraordinarily high conductivity. Growing graphene is not very easy though, as impurities can easily impair the very abilities people want. Researchers at the University of Illinois at Urbana-Campaign have discovered a link, for one growth method, between the substrate graphene is grown on and the quality of the grown graphene. The method involves pumping methane gas (comprised of one carbon atom and four hydrogen atoms, per molecule) into a furnace with copper foil in it. When the methane strikes the copper, its hydrogen atoms are stripped away, leaving the carbon atom on the copper sheet. By imaging the crystalline structures of the foil, the researchers found a correlation between the kinds of structure and the graphene quality. Structure index 100 was horrible for producing graphene, as gaps in the structure allowed the carbon to build up vertically, instead of horizontally. Structure 111 however, with a dense hexagonal pattern to the copper atoms, was the best at producing graphene, which also has a hexagonal structure. It is not clear if the similarity in structure is what causes this. While a better means to produce high quality graphene would be of great use to those wanting to replace silicon with graphene, creating copper foils with a higher concentration of structure 111 is expensive. Still, this research shows great promise as researchers across the world are working hard to find the best means of making graphene.