Tuning the plasmon resonance of metallic tin nanocrystals in Si-based materials

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.