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Descripción
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| Si oxide films with a controlled excess of Si were deposited on Si wafers by LPCVD using Si2H6 and O2, thermally annealed to 1100 ºC for 1 h to form Si nanocrystals embedded in SiO2 and annealed at 450 ºC in forming gas (FG). The samples were characterized by spectroscopic ellipsometry (SE) and cathodoluminescence (CL). The growth rate, the excess of Si and the luminescence intensity were modelled using a Central Composite Design (pressure: 185-300 mTorr, temperature: 250-400 ºC, Si2H6/O2 flow ratio: 0.2-5). Simulations of the SE measurements using either Cauchy functions or Maxwell-Garnett mixtures of the optical properties of Si and SiO2 were carried out to derive the n and k spectra. The excess of Si in the as deposited samples, ranging from 0 to 47 % in volume, was obtained from n. Si nanocrystals were detected in the annealed samples by the existence of an absorption band at around 300 nm. The CL spectra measured at 80 K show a broad band at 500 nm, which can be attributed to the oxide matrix, and a sharp peak at 650 nm due to the presence of Si nanocrystals. At RT, the spectra show only the 650 nm peak, with a lower intensity than at 80 K, while the emission arising from the oxide is quenched. The intensity of the main peak increases with the Si content, reaches a maximum and decreases again in the samples with the highest excess of Si. The treatments in FG cause the intensity of this peak to increase with the annealing time due to the passivation of dangling bonds. | |
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Internacional
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Si |
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Nombre congreso
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Europena Material Research Society 2007 Spring Meeting |
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Tipo de participación
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960 |
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Lugar del congreso
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Estrasburgo/Francia |
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Revisores
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Si |
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ISBN o ISSN
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0000000000000000000 |
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DOI
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Fecha inicio congreso
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28/05/2007 |
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Fecha fin congreso
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01/06/2007 |
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