Enhancement of photoluminescence from silicon nanocrystals by metal nanostructures made by nanosphere lithography

The effect of metal nanostructures prepared by nanosphere lithography on photoluminescence (PL) properties of silicon nanocrystals (Si-ncs) is studied. By placing Ag nanotriangles or Au nanovoids on SiO(2) films containing Si-ncs, the PL intensity is enhanced. For the sample having Ag nanotriangles, the largest PL enhancement is obtained when the excitation wavelength coincides with the absorption band of Ag nanotriangles. This suggests that the enhancement of the incident field by surface plasmon polariton (SPP) excitation is responsible for the PL enhancement. On the other hand, for the sample having Au nanovoids, the PL enhancement is mainly made by the enhancement of effective radiative decay rate of Si-ncs by efficient excitation and scattering of SPPs.