Researchers at the Forschungszentrum JÃ¼lich developed a criterion to help scientists identify suitable substrate materials for graphene in a targeted way, in hopes to deal with the known problem of interactions with the substrate material that lead to a loss of graphene's remarkable properties. Together with partners at other institutions, the scientists were able to demonstrate that the influence exerted by the substrate on the electronic properties of graphene can be estimated by means of a simple structural parameter.
The scientists set out to find an accessible parameter which can be used to compare different substrates directly, and the decisive criterion turned out to be the atomic distance between the graphene layer and the underlying substrate. Considering the van der Waals radiusâa known value for the size of atoms in their free stateâthe strength of the interaction can be calculated directly from the distance. Computer simulations confirm this result.
The scientists claim that it is time for a new criterion such as this, with which even very weak interactions can be detected precisely, and with the techniques available so far (photoelectron spectroscopy, for example) the degree of interaction with the substrate could only be deduced indirectly.