Infrared surface plasmons in two-dimensional silver nanoparticle arrays in silicon

We present two-dimensional arrays of silver nanoparticles embedded in amorphous silicon, fabricated by a sequential $\mathrm{Si}∕\mathrm{Ag}∕\mathrm{Si}$ electron-beam evaporation process. The particle arrays exhibit surface plasmon resonance spectra in the near-infrared $\left(0.9\mathrm{eV}\right)$ , with tails extending below $0.5\mathrm{eV}$ . The data are compared with calculations that take into account measured particle size, shape anisotropy, and separation. It is concluded that the large redshift is mainly due to the high refractive index of the matrix, with shape anisotropy and interparticle coupling contributing several tenths of an electron volt. This work enables plasmon-related applications at the telecommunication wavelength of $1.5\mu \mathrm{m}\left(0.8\mathrm{eV}\right)$ .