Residual stress in Si nanocrystals embedded in a $SiO2$ matrix

Multiple quantum wells consisting of alternating Si and $SiO2$ layers were studied by means of Raman scattering. The structures were fabricated by the remote plasma enhanced chemical vapor deposition of amorphous Si and $SiO2$ layers on quartz substrate. The structures were subjected to a rapid thermal annealing procedure for Si crystallization. The obtained results suggest that the Si layers consist of nanocrystals embedded in an amorphous Si phase. It was found that the silicon nanocrystals inside $2nm$ thin layers are under high residual compressive stress. Moreover, the metastable Si III phase was detected in these samples supporting the presence of large compressive stresses in the structures. The compressive stress could be relaxed upon local laser annealing.