  The optical properties of metallic tin nanoparticles embedded in
silicon-based host materials were studied. Thin films containing the
nanoparticles were produced using RF magnetron sputtering followed by ex situ
heat treatment. Transmission electron microscopy was used to determine the
nanoparticle shape and size distribution; spherical, metallic tin nanoparticles
were always found. The presence of a localized surface plasmon resonance in the
nanoparticles was observed when SiO2 and amorphous silicon were the host
materials. Optical spectroscopy revealed that the localized surface plasmon
resonance is at approximately 5.5 eV for tin nanoparticles in SiO2, and at
approximately 2.5 eV in amorphous silicon. The size of the tin nanoparticles in
SiO2 can be varied by changing the tin content of the films; this was used to
tune the localized surface plasmon resonance.
