Morphological and RF Characterization of graphene composite films

Graphene is a monolayer of carbon atoms which exhibits remarkable electronic and mechanical properties. Graphene based nano-materials have gained a lot of interest for many applications. In this paper, a graphene inks with three concentrations (25 % in weight and 33 % in weight) were prepared and deposited, by screen printing. A detailed investigation of the surface morphology of the films using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM) revealed that the graphene films present a homogeneous dispersion of the filler with a comparatively lower surface roughness at higher concentrations, and negligible agglomerates. The films were then printed between copper electrodes on FR-4 substrate, commonly used in RF circuits, and the measured scattering parameters analysed. Finally, the reflection coefficient of a patch antenna, fabricated on FR-4 substrate with and without a stub loaded by a thin film were measured. The shift of the resonant frequency due to the presence of the graphene film (i.e. 430 MHz) shows attractive features of functionalized graphene films for chemical and bio-sensing applications.