Ewald Janssens1 Jeroen Scheerder1 Joris Van de Vondel1

1, KU Leuven, Leuven, , Belgium

Graphene’s two-dimensional nature makes it very susceptible to adparticles: adsorbed atoms or molecules, either individual or clustered. For instance, graphene’s electronic properties have been shown to be susceptible to gas molecule adsorption with a sensitivity down to single molecule detection.1 Conversely, the properties of deposited zero-dimensional adparticles are strongly affected by the interaction with the support. In a graphene–adparticle system, both low-dimensional components define the characteristics of this hybrid structure.

Small metallic clusters exhibit distinct electronic and structural properties, that vary in a non-scalable way with their size. Theoretical investigations of well-defined few-atom metallic clusters as adparticles on graphene suggest that the cluster’s size-dependent properties get carried over in, for instance, graphene’s electronic properties.2

We investigated the interaction between size-selected Au2, Au3, and Au6 clusters and graphene. Hereto
preformed clusters are deposited on graphene field-effect transistors, an approach which offers a high control over the number of atoms per cluster, the deposition energy and the deposited density.3 In situ electronic transport measurements on cluster-graphene devices show that charge transfer between the clusters and the graphene leads to p-doping and enhanced charge carrier scattering. The results also indicate that a major part of the deposited clusters remains on the graphene flake as either individual entities. Cluster size dependencies are correlated with the electronic structure of the isolated clusters.

This approach provides perspectives for electronic and chemical sensing of metallic clusters down to their atom-by-atom size-specific properties, and exploiting the tunability of clusters for tailoring desired properties in graphene.

1 F. Schedin, A. K. Geim, S. V. Morozov, E. W. Hill, P. Blake, M. I. Katsnelson and K. S. Novoselov, Nat. Mater. 6 (2007) 652.
2 M. K. Srivastava, Y. Wang, A. F. Kemper and H.-P. Cheng, Phys. Rev. B 85 (2012) 165444.
3 J.E. Scheerder, T. Picot, N. Reckinger, T. Sneyder, V.S. Zharinov, J.F. Colomer, E. Janssens, and J. Van de Vondel, Nanoscale 9 (2017) 10494.