Researchers from the Rice University and Hong Kong Polytechnic University have collaborated with each other to demonstrate that arrays of graphene nanoribbons can be stacked up to create a wall, which can be made to stand on a substrate.
Researchers at Rice University and Hong Kong Polytechnic University calculated that graphene nanoribbons could stand up on diamond or nickel, or even form arches. Up to 100 trillion graphene walls could fit on a square centimeter chip. Credit: Feng Ding/Hong Kong Polytechnic University
Graphene sheets arranged in such a manner have shown electrical properties thus leading to the possibility of creating components with a high level of density for electronic devices.
Researchers have been able to establish that substrates could be created from diamond or nickel. Both diamond and nickel have the ability to bind well with the carbon molecules present in the corners of the graphene stacks with little support. It was discovered that carbon molecules bound the most with the diamond substrate when the graphene nanoribbons were stacked at a 90° angle. On the nickel substrate, maximum binding was achieved when the graphene nanoribbon walls were stacked at a 30° angle. In order to retain the electrical conductivity of each nanoribbon, the graphene walls had to be kept at a distance of 7/10ths of a nanometer. Aluminium oxide, silicon carbide, silicon and silicon dioxide are other materials, on which graphene nanoribbon walls can be created.
Graphene walls can be stacked in a zig-zag or armchair formation. While armchair nanoribbons can act as semiconductors that can be used in transistors, zig-zag nanoribbons display magnetic properties, making them useful in spintronic devices. As graphene nanoribbons are thin, researchers suggest that 100 trillion graphene wall field-effect transistors could be assembled on one chip measuring a square centimetre.