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Descripción
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| Si, SiGe and Ge nanoparticles embedded in an oxide matrix are highly interesting for applications in luminescent devices compatible with CMOS technology. A promising method for the production of SiGe nanoparticles is the deposition of discontinuous layers of SiGe sandwiched by SiO2 using a conventional hot tube Low Pressure Chemical Vapor Deposition reactor. However, the deposited layers have to be subjected to a heat treatment to show the desired luminescent emission. These annealing processes may lead to unwanted composition changes and diffusion. For the present study multilayer structures with five periods of amorphous SiGe nanoparticles/SiO2 and a top SiO2 capping layer with different thickness were deposited in order to increase the area density of SiGe nanoparticles. The use of grazing incidence RBS was, due to the extremely small nominal thickness of the SiGe-layers (less than a monolayer) and SiO2 interlayers, the only possibility to investigate the details of composition changes and diffusion processes occurring in these multilayer systems. The application of a model for the RBS analysis, recently developed by the authors, allowed the determination of the average size and area density of the embedded nanoparticles. Transmission Electron Microscopy (TEM) was used to obtain complementary information on the size and crystallinity of the nanoparticles. The RBS study revealed that annealing at 900ºC for 60 seconds causes a strong degradation of multilayer structures with thin SiO2 interlayers due to Ge diffusion. In samples with thicker interlayers for the same annealing conditions the degradation is limited or absent. High Resolution TEM micrographs of the latter samples showed that the annealing leads to the crystallization of the nanoparticles but leaves their area density or size unaltered. These results enabled to determine the combination of SiGe- and SiO2-layer thickness for which the luminescence yield is maximized. | |
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Internacional
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Si |
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Nombre congreso
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18th International Conference on Ion Beam Analysis |
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Tipo de participación
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960 |
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Lugar del congreso
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Hyderabad, India |
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Revisores
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Si |
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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23/09/2007 |
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Fecha fin congreso
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28/09/2007 |
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