PROPERTIES OF LUMINESCENT SI NANOPARTICLES IN SOL-GEL MATRICES

In this work, the preparation and properties of silica sol-gels incorp orating luminescent Si nanocrystallites extracted from porous Si are d escribed for the first time. These sol-gel/Si nanocrystallite composit e materials are characterized by BET isotherm measurements, photolumin escence spectroscopy, and infrared spectroscopy. To stabilize the phot oluminescence (PL) of Si crystallites within the silica matrix, a fatt y acid (capric (Clo), myristic (C-14) Or arachidic acid (C-20)) is add ed as a passivation agent during the hydrolysis of tetraethoxysilane. The presence of the fatty acid is crucial to the long-term stability o f the Si nanocrystallite luminescence, as the Si visible light emissio n remains essentially unchanged for more than a month when the fatty a cid is present in the mixture but degrades quickly (within days) when absent. The thermal stability of the Si luminescence within the sol-ge l is also reported. Fluorescence microscopy reveals that the light-emi tting Si crystallites aggregate into micron-sized domains somewhat une venly throughout the silica matrix. This distribution of Si crystallit es can be improved by employing a surfactant, dioctyl sodium sulfosucc inate (DSS).