Hot spot statistics and SERS performance of self-assembled silver nanoisland films

The statistics of hot spots in the ensemble of self-assembled silver nanoislands grown on the surface of silver-to-sodium ion exchanged glass under hydrogen annealing was studied. The comparison of the surface enhanced Raman scattering (SERS) performance of the nanoisland films at different growth stages with the developed model of the hot spots formation revealed that at the nanoislands coalescence stage the enhancement is dominated by the increase of electric field in the hot spots, not by their surface density. At earlier growth stages, the linear relation between the SERS signal and the hot spots surface density is expected.