Surface resonance properties of thin silver films with nanoparticles induced by pulsed-laser interference dewetting process

Pure Ag thin films with a thickness of 10 nm were deposited on glass substrates using a thermal evaporator system. Nanoparticles were then induced in the films by a Michelson interferometer dewetting process. The particle size was found to decrease with an increasing laser power and exposure time. The minimum particle size was 150 nm for a laser power of 4 W and exposure time of 60 s. However, a smaller particle size of 110 nm was obtained by adopting a two-step exposure process with a rotation angle of 30° and an exposure time of 55 s. The absorption peak wavelength of the dewetted films increased with an increasing rotation angle. By contrast, a blue shift in the absorption spectrum occurred as the laser power increased. The half-height widths of the absorption peaks of the films dewetted using different rotation angles were wider than those of the films dewetted without rotation, indicating that the two-step rotation process resulted in a wider particle size distribution. Overall, the results show that the optical properties of the laser-dewetted Ag films are highly dependent on the interference parameters.