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- Nestoklon, Mikhail O., et al.
(author)
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Tight-binding calculations of the optical properties of Si nanocrystals in a SiO(2)matrix
- 2020
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In: Faraday discussions. - : Royal Society of Chemistry (RSC). - 1359-6640 .- 1364-5498. ; 222:0, s. 258-273
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Journal article (peer-reviewed)abstract
- We develop an empirical tight binding approach for the modeling of the electronic states and optical properties of Si nanocrystals embedded in a SiO(2)matrix. To simulate the wide band gap SiO(2)matrix we use the virtual crystal approximation. The tight-binding parameters of the material with the diamond crystal lattice are fitted to the band structure of beta-cristobalite. This model of the SiO(2)matrix allows us to reproduce the band structure of real Si nanocrystals embedded in a SiO(2)matrix. In this model, we compute the absorption spectra of the system. The calculations are in an excellent agreement with experimental data. We find that an important part of the high-energy absorption is defined by the spatially indirect, but direct ink-space transitions between holes inside the nanocrystal and electrons in the matrix.
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