2021 Spring Meeting of the European Materials Research Society (E-MRS) will be held as a virtual conference from May 31 to June 3, 2021.

Ilka Hermes, principal scientist at Park Systems Europe will present a talk on “Resolving graphene´s heterogeneous surface potential distribution”. Please see the abstract below.

Time & Place: 2 June at 12.45 pm, Symposium F. Talk number: F.4.13.

Link: hhttps://www.european-mrs.com/meetings/2021-spring-meeting-0  

ABSTRACT

Resolving graphene´s heterogeneous surface potential distribution

Authors: Ilka M. Hermes¹; Simonas Krotkus²; Michael Heuken²; Ben Conran³; Clifford McAleese³; Xiaochen Wang³; Oliver Whear³

¹Park Systems Europe GmbH, Mannheim, Germany; ²AIXTRON SE, Herzogenrath, Germany; ³AIXTRON Ltd, Cambridge, United Kingdom

The application of graphene for energy conversion applications often requires functionalization via covalent binding or adsorption to tune the material´s electronic properties. To achieve a uniform functionalization, the local surface properties of the pristine graphene can be decisive. Therefore, real-space imaging of the graphene topography as well as mapping the electronic properties with a nanometer resolution is essential. Atomic force microscopy (AFM) not only visualizes surface topography, but can additionally resolve functional properties, such as the surface potential and work function, adhesion and elasticity. 
Here, we investigated electronic and mechanical properties of a CVD grown wafer scale graphene film on sapphire via functional AFM techniques. In particular, using sideband Kelvin probe force microscopy (KPFM) we were able to resolve a heterogeneous surface potential distribution with distinct contrast between the bulk film, graphene wrinkles as well as on the underlying sapphire terraces and step edges. The surface potential distribution correlated with the mechanical behavior, including deformation and adhesion, which gave a distinct contrast on the same features, resolved via PinPoint nanomechanical AFM. The correlation of the surface potential and the sample´s nanomechanical response likely originates from delamination. Especially the local change of the surface potential has to be considered when functionalizing the graphene surface for energy applications. 

Figure caption: Topography and surface potential captured via sideband KPFM on CVD-grown graphene on a sapphire substrate.