Infrared photoluminescence from GeSi nanocrystals embedded in a germanium-silicate matrix.
Résumé
We investigate the structural and optical properties of GeO/SiO multilayers obtained by evaporation of GeO and SiO powders under ultrahigh vacuum conditions on Si(001) substrates. Both Raman and infrared absorption spectroscopy measurements indicate the formation of GeSi nanocrystals after postgrowth annealing at 800°C. High-resolution transmission electron microscopy characterizations show that the average size of the nanocrystals is about 5 nm. For samples containing GeSi nanocrystals, photoluminescence is observed at 14 K in the spectral range 1500-1600 nm. The temperature dependence of the photoluminescence is studied.