Engineering microscale two-dimensional gold nanoparticle cluster arrays for advanced Raman sensing: An AFM study

We realized and tested a strategy for developing reproducible and stable two-dimensional gold nanoparticle cluster arrays arranged on silicon substrates, to be used for surface-enhanced Raman spectroscopy. We combined electron beam lithography and molecular functionalization to finely control the shape of the nanoparticle assemblies. Atomic force microscopy analysis allowed to optimize the procedure of nanoparticle cluster array fabrication in terms of electron beam dose and chemical protocol, enabling to achieve a good regularity in spacing and size (i.e. area and layer number) of the clusters. MicroRaman space resolved measurements were undertaken on large 2D arrays (100 × 100 µm2) made up of regularly microsized clusters. The high surface enhanced Raman signal measured on the structures highlights the full correspondence of the spatial and optical periodicity achieved. This standardized procedure represent the basis to realize versatile platforms for nano-optical investigation and towards an efficient high-sensitive multiplex sensing.