Single atom contacts developed between graphene and gold

A team of researchers from Aalto and Utrecht universities have demonstrated experimentally how this can be done, creating single atom contacts between gold and graphene nanoribbons. Professor Peter Liljeroth, who heads the Atomic Scale Physics group at Aalto University, said: "We cannot use alligator clips on the atomic scale. Using well defined chemical bonds are the way forward for graphene nanostructures to realise their potential in future electronics." The team used atomic force (AFM) and scanning tunnelling microscopes (STM) to map the structure of the graphene nanoribbons with atomic resolution. The researchers then used voltage pulses from the tip of the STM to form single bonds to the graphene nanoribbons –at specific atomic locations. The pulse removed one hydrogen atom from the end of a graphene nanoribbon and that initiated bond formation. Dr Ingmar Swart who leads the team concentrating on STM and AFM measurements at Utrecht University, added: "Combined AFM and STM allows us to characterise the graphene nanostructures atom by atom, which is critical in understanding how the structure, the bonds with the contacts and their electrical properties are related." The most significant discovery from the research is that a single chemical bond forms an electronically transparent contact with the graphene nanoribbon without affecting its overall electronic structure. This, says the team, may be the key to using graphene nanostructures in future electronic devices as the contact does not change the ribbon's intrinsic properties.