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Title: Tailoring the surface density of silicon nanocrystals embedded in SiOx single layers
Author: Hernández Márquez, Sergi
Miska, P.
Grün, M.
Estradé Albiol, Sònia
Peiró Martínez, Francisca
Garrido Fernández, Blas
Vergnat, M.
Pellegrino, Paolo
Keywords: Silici
Nanocristalls semiconductors
Cèl·lules solars
Microscòpia electrònica de transmissió
Semiconductors amorfs
Semiconductor nanocrystals
Solar cells
Transmission electron microscopy
Amorphous semiconductors
Issue Date: 25-Oct-2013
Publisher: American Institute of Physics
Abstract: In this article, we explore the possibility of modifying the silicon nanocrystal areal density in SiOx single layers, while keeping constant their size. For this purpose, a set of SiOx monolayers with controlled thickness between two thick SiO2 layers has been fabricated, for four different compositions (x=1, 1.25, 1.5, or 1.75). The structural properties of the SiO x single layers have been analyzed by transmission electron microscopy (TEM) in planar view geometry. Energy-filtered TEM images revealed an almost constant Si-cluster size and a slight increase in the cluster areal density as the silicon content increases in the layers, while high resolution TEM images show that the size of the Si crystalline precipitates largely decreases as the SiO x stoichiometry approaches that of SiO2. The crystalline fraction was evaluated by combining the results from both techniques, finding a crystallinity reduction from 75% to 40%, for x = 1 and 1.75, respectively. Complementary photoluminescence measurements corroborate the precipitation of Si-nanocrystals with excellent emission properties for layers with the largest amount of excess silicon. The integrated emission from the nanoaggregates perfectly scales with their crystalline state, with no detectable emission for crystalline fractions below 40%. The combination of the structural and luminescence observations suggests that small Si precipitates are submitted to a higher compressive local stress applied by the SiO2 matrix that could inhibit the phase separation and, in turn, promotes the creation of nonradiative paths.
Note: Reproducció del document publicat a:
It is part of: Journal of Applied Physics, 2013, vol. 114, p. 233101-1-233101-6
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ISSN: 0021-8979
Appears in Collections:Articles publicats en revistes (Enginyeria Electrònica i Biomèdica)
Publicacions de projectes de recerca finançats per la UE

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