Tuning defect-related photoluminescence of Ge nanocrystals by stress

Ge nanocrystals embedded in SiO₂ and Lu₂O₃ thin films were fabricated using a pulsed laser deposition method. Two dimensional finite element calculations and Raman spectra clearly revealed that the Ge nanocrystals certainly experienced greater compressive stress in a Lu₂O₃ thin film than in a SiO₂ thin film. This may lead to much more stress-relaxing defects at the interface of Ge nanocrystals embedded in a Lu₂O₃ thin film and thus enhances the intensity of defect-related photoluminescence. The findings presented here indicate that the matrix environment of the nanocrystals plays a significant role in the defect-related photoluminescence property.