In situ SEM/AFM characterisation of hybrid structures made of graphene-veiled gold nanoparticles for bio sensing
The combination of gold nanoparticles and graphene veiling is a novel approach to fabrication of active substrates suitable for Surface Enhanced Raman Spectroscopy (SERS). Graphene can serve as a pin-hole passivation layer, which prevents plasmonic nanostructures from oxidizing. The level of the contact between Au particles and graphene plays a significant role in the sensitivity of SERS. Therefore, it is important to know the way a graphene membrane veils a single nanoparticle or a cluster of such nanoparticles. The distribution of the nanoparticles under the graphene membrane as well as the surface topography can be easily determined using CPEM – Correlative Probe and Electron Microscopy™. While LiteScope™ SPM (AFM) can image the surface of a graphene layer on top of nanoparticles, SEM can image nanoparticles under the graphene layer. AFM images show that graphene does not completely wrap the nanoparticles, this results in reduced SERS effect.