ABSTRACT
Silicon nanocrystals (Si-nc) embedded in silica films are studied
by optical spectroscopy and a number of other methods. Spectral
filtering of photoluminescence by silica films containing Si-nc is
described and used to measure the optical properties of the film
material. In particular, optical birefringence is found for some
samples and connected with the nonspherical shape of Si-nc. The
correlations between the optical and structural properties suggest
the photoluminescencemechanism involving oxygen-related defects
or ultrasmall Si grains. The effect of continuous-wave laser annealing
on structural and optical properties of free-standing silica films
containing Si-nc is described in detail. The results obtained show
very efficient Si-SiO2 phase separation by laser annealing, which
leads to the formation of large Si-nc (∼100 nm in diameter) and strongly increases the Raman scattering of these films due to
the resonance size effect. Compressive stress of the large Si-nc
evidenced by Raman spectroscopy is produced due to Si melting
by laser light, and this stress can be reduced by laser annealing at
lower temperatures. The compressive stress is not observed for Si-
nc located near the film surface, which is explained by nano-eruption
of Si pressurized at the solidification stage.
