James Tour, a lab chemist at the Rice University, has published two research papers that describe novel production technologies of superior-quality bilayer graphene in a large scale that involves growing it on on various insulating substrates directly.
‘Growth of Bilayer Graphene on Insulating Substrates’ and ‘Direct Growth of Bilayer Graphene on SiO2 Substrates by Carbon Diffusion Through Nickel’ are the titles of the two papers, which describe the methods used to develop bilayer graphene on a functional substrate by first making it to diffuse onto a nickel layer.
Novel methods allow bilayer graphene to grow directly onto a variety of insulating substrates. Credit: Tour Lab/Rice University
Tour stated that the novel processes’ ability to develop bilayer graphene straightaway onto a insulating substrate can allow electronics device producers to eliminate the troublesome process of stacking graphene sheets on one another while building transistors. The novel methods are based on carbon atom solubility in heated nickel.
In the first study, a nickel coating is evaporated onto silicon dioxide and a polymer film is placed on top. The polymer is diffused into the metal when the sandwich structure is heated to 1,000° C in a stream of hydrogen and argon gases. When the sandwich structure is cooled, graphene is obtained on the silicon dioxide and the nickel surfaces. Upon etching away of the nickel and incidental graphene that are created on top, bilayer graphene remained on the silicon dioxide substrate. The research was supported by the Air Force Office of Scientific Research, Lockheed Martin and Office of Naval Research MURI program.
In the second study, the researchers sandwiched a polymer layer between the silicon dioxide and nickel. When low pressure and high temperature is applied, bilayer graphene is formed between the nickel and silicon dioxide. The researchers also demonstrated that bilayer graphene can also be formed on sapphire, silicon nitride and hexagonal boron nitride. The research was supported by M-I SWACO, the Air Force Office of Scientific Research, the Air Force Research Laboratory via United Technology Corp. and the Office of Naval Research MURI program.