The local environment of light emitting silicon nanocrystals (Sync) embedded in amorphous SiO2 has been studied by x-ray absorption spectroscopy (XAS) and by ab-initio total energy calculations. Si-nc have been formed by PECVD deposition of SiOx with different Si content (from 35 to 42 at.%) and thermal annealing at high temperature (1250 C). The comparison between total electron yield (TEY) and photoluminescence yield (PLY) spectra has allowed the identification of a modified region of SiO2 (about 1 nm thick) surrounding the Si-nc, which participates to the light emission of Si-nc. Total energy calculations, within the density functional theory, clearly show that Si-nc are surrounded by a cap-shell of stressed SiO2 with a thickness of about 1 run. The optoelectronic properties show the appearance of localized states not only in the Sinc core region but also in the modified SiO2 region.

Experimental and theoretical joint study on the electronic and structural properties of silicon nanocrystals embedded in SiO2: Active role of the interface region

Daldosso, Nicola;
2003

Abstract

The local environment of light emitting silicon nanocrystals (Sync) embedded in amorphous SiO2 has been studied by x-ray absorption spectroscopy (XAS) and by ab-initio total energy calculations. Si-nc have been formed by PECVD deposition of SiOx with different Si content (from 35 to 42 at.%) and thermal annealing at high temperature (1250 C). The comparison between total electron yield (TEY) and photoluminescence yield (PLY) spectra has allowed the identification of a modified region of SiO2 (about 1 nm thick) surrounding the Si-nc, which participates to the light emission of Si-nc. Total energy calculations, within the density functional theory, clearly show that Si-nc are surrounded by a cap-shell of stressed SiO2 with a thickness of about 1 run. The optoelectronic properties show the appearance of localized states not only in the Sinc core region but also in the modified SiO2 region.
porous silicon; EXAFS; luminescence; XEOL
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11562/477112
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