Nanoindentation of Si Nanocrystals in SiO2

Nanoindentation is used to investigate the effects of mechanical deformation on systems of silicon nanocrystals (Si-nc) embedded in SiO ₂. The process is found to introduce non-radiative defects to the crystals which quench their luminescence in the localised region of the indent. The transformation to high-pressure metastable phases in the underlying Si substrate is characterised by Raman spectroscopy and transmission electron microscopy, with the critical load found to be between 50 and 100 mN for a spherical indenter and between 25 and 50 mN for a Berkovich indenter. The results are consistent with computer simulations of the indentation process on identical systems