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Descripción
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| Nanoparticles of the Group IV semiconductors embedded in a dielectric SiO2 matrix have received a great deal of attention because of their potential applications in optoelectronic devices and non-volatile memories. Several approaches have been tried to make nanocrystalline structures inside the dielectric matrix, like ion implantation, sputtering or Chemical Vapour Deposition. Usually, Si or Ge nanocrystals are formed. However, previous attempts to prepare arrays of SiGe nanocrystals revealed that the diffusion of Ge constitutes a drawback to control the nanocrystal composition. Intense luminescence is required for light emission applications; therefore, a high density of nanocrystals is desirable. For these purposes we have fabricated multilayer arrangements of SiGe nanocrystals, obtained by rapid thermal crystallization (temperatures between 750 and 1100 °C, and times up to 10 minutes) of amorphous nanoparticles embedded in a matrix of SiO2 deposited by low pressure chemical vapour deposition (LPCVD). This process is fully compatible with the CMOS technology. The structures were characterized by Raman spectroscopy, Rutherford Backscattering Spectrometry, Transmission Electron Microscopy, Fourier transform infrared spectroscopy and Cathodoluminescence. The effect of the annealing conditions and the thickness of the oxide interlayers on the luminescence intensity and on the variation of the composition of the nanocrystals due to the Ge diffusion were studied. The contributions of the SiO2 matrix and the SiGe nanoparticles to the luminescence were identified and separated. The maximum intensity of the luminescence has been obtained after annealing the samples at 900 °C. At this temperature the SiGe nanoparticles are fully crystallized and no appreciable variation of their composition has been detected. The luminescence of the structures increases: a) with the number of periods in the structure and b) with the thickness of the SiO2 interlayers. The luminescence emission was compared to our previous results for pure Ge nanocrystals, showing that the light emission mechanisms are similar for both SiGe and Ge nanocrystals. | |
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Internacional
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Si |
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JCR del ISI
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Si |
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Título de la revista
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AAPG BULL |
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ISSN
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978-1-55899-915-2 |
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Factor de impacto JCR
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1,273 |
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Información de impacto
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Volumen
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DOI
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Número de revista
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958 |
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