Ag films annealed in a nanoscale limited area for surface-enhanced Raman scattering detection

By constructing a limited two-dimensional (2D) area to regulate the coalescence of deposited Ag nanoparticles and to change the degree of aggregation of nanoparticles under annealing, a configuration of particles on pillar (POP) was fabricated successfully and high SERS enhancement similar to 'hot spots' was generated on the POP. With the assistance of nanosphere lithography (NSL), we constructed a silicon pillar array with a column diameter of 200 nm and a height of 155 nm. A thin layer of Ag film with a several nanometer thickness was deposited on the top of the silicon pillar array and then was annealed under 200 °C. Differing from the annealed Ag on a flat surface, the aggregation of Ag on the top of a pillar was predominated by the limited area, forming more Ag nanoaggregates. The SERS spectra demonstrated that the POP contributed to higher SERS enhancement than the silicon slide modified by the some thickness annealed Ag film. As a consequence, by means of POP configuration, the lowest SERS detection concentration for 4-mercaptopyridine was able to reach the level of 1.0 × 10(-10) M.