Direct bandgap optical transitions in Si nanocrystals
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- Prokofiev, A.A., Moskalenko, A.S., Yassievich, I.N. et al. Jetp Lett. (2010) 90: 758. doi:10.1134/S0021364009240059
The effect of quantum confinement on the direct bandgap of spherical Si nanocrystals has been modelled theoretically. We conclude that the energy of the direct bandgap at the Γ-point decreases with size reduction: quantum confinement enhances radiative recombination across the direct bandgap and introduces its “red“ shift for smaller grains. We postulate to identify the frequently reported efficient blue emission (F-band) from Si nanocrystals with this zero-phonon recombination. In a dedicated experiment, we confirm the “red“ shift of the F-band, supporting the proposed identification.