Three tier graphene films can be produced at commercial scale

By arranging these layers in a particular format, they were able to produce a much desired band gap - an energy range that falls between the bands, or energy levels, where electrons can exist in a given material. The research team says the new method makes it possible to produce the precise arrangement of the layers, called A-B stacked, opening up the possibility of graphene being used in future electronic and optoelectronic devices. "Our method takes advantage of a technique originally developed as far back as the 1950s," explained Michael Strano, an Associate Professor of Chemical Engineering at MIT. "Compounds of bromine or chlorine were introduced into a block of graphite and naturally found their way into the structure of the material, inserting themselves regularly between every other layer, or in some cases every third layer, pushing the layers slightly farther apart in the process." Strano and his team found that when the graphite was dissolved, it naturally came apart where the added atoms were, forming graphene flakes two or three layers thick. "Because this dispersion process can be very gentle, we ended up with much larger flakes than anyone has made using other methods," he claimed. The researcher believes such formations are one of the most promising candidates for post silicon nanoelectronics to date. "The flakes produced by this method, as large as 50 square micrometers in area, are large enough to be useful for electronic applications," he said. "We have even been able to manufacture some simple transistors on the material." While Strano did not give a time scale as to when the method will be ready for commercial application, he says the research is coming along at a 'bottleneck' pace. "A similar solvent based method for making single layer graphene is already being used to manufacture some flat screen television sets, and this is definitely a big step towards making bilayer or trilayer devices," he concluded. The research has been published in the journal Nature Nanotechnology.