I prepared samples with silver nanoparticles obtained by metal island film (MIF) method.
Samples annealed at the 400 Celsius degrees revealed reduction of reflection of Si wafer and change in position of reflection minima due to the change in plasmon resonance for different samples. Highest reflection reduction was obtained for 17 nm initial Ag layer.

By SEM observations average paricles size was found:
120 - 135 nm for inintial 11nm,
130 - 140 nm for initial 14nm,
150 - 170 nm for initial 17 nm,
180 - 200 nm for initial 20 nm.

This corresponds with optical properties of the prepared samples