Tailoring the surface density of silicon nanocrystals embedded in SiO{sub x} single layers
- Electronics Department, MIND–IN2UB, Universitat de Barcelona, Martí i Franquès 1, E–08028 Barcelona, Catalonia (Spain)
- Institut Jean Lamour, Université de Lorraine, CNRS UMR 7198—Faculté des Sciences et Technologies, B.P. 70239, F-54506 Vandoeuvre-lès-Nancy (France)
In this article, we explore the possibility of modifying the silicon nanocrystal areal density in SiO{sub x} single layers, while keeping constant their size. For this purpose, a set of SiO{sub x} monolayers with controlled thickness between two thick SiO{sub 2} layers has been fabricated, for four different compositions (x = 1, 1.25, 1.5, or 1.75). The structural properties of the SiO{sub 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{sub x} stoichiometry approaches that of SiO{sub 2}. 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 SiO{sub 2} matrix that could inhibit the phase separation and, in turn, promotes the creation of nonradiative paths.
- OSTI ID:
- 22266130
- Journal Information:
- Journal of Applied Physics, Vol. 114, Issue 23; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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