On the role of non-bridging oxygen centers in the red luminescence emission from silicon nanocrystals

Elisabetta Borsella, Rosaria D'Amato, Fabio Fabbri, Mauro Falconieri, Enrico Trave, Valentina Bello, Giovanni Mattei, Yaru Nie, Dayang Wang

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Abstract

The process responsible for visible-near infrared luminescence emission in Si nanostructures has been generating significant controversy for years. The debate has focused on whether light emission is originated by recombination of quantum confined excitons or by defects located at the surface. It is experimentally difficult to distinguish the two contributions since both are size-dependent. Moreover, all the studies were performed on different systems and consequently the comparisons were not free from ambiguities. Here we relate the spectroscopic properties of pyrolytic Si nanocrystals, aged in air, and after complete conversion to amorphous silica by alkali etching-assisted oxidation. The strong resemblance of the spectral and time decay behavior of the red PL emission in both systems (surface oxidized nanocrystalline Si and amorphous silica sample) indicates that this emission is dominated by defects in the silicon oxide. The strongly non-exponential time behavior of the photo-luminescence emission in both systems can be modeled as the sum of exponential decays from the emitting defects, thus ruling out the interpretation in terms of the so-called "stretched exponential" decay. Using this model we also obtained the emission energy and inhomogeneous linewidth of the luminescent defects, allowing us to identify them as the non-bridging oxygen hole centers. The emission energy of these defects depends strongly on their physical and chemical environment and can produce a shift apparently due to the size effect. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Original languageEnglish
Pages (from-to)974 - 978
Number of pages5
JournalPhysica Status Solidi (C) Current Topics in Solid State Physics
Volume8
Issue number3
DOIs
Publication statusPublished - Mar 2011
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

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