Optical absorption and emission of silicon nanocrystals: From single to collective response

Abstract

We report on the possibility of describing the absorption and emission characteristics of an ensemble of silicon nanocrystals (NCs) with realistic distributions in the NC size, by the sum of the reponses of the single NCs. The individual NC responses are evaluated by means of ab initio theoretical calculations and the summation is performed by taking into account the trend of the optical properties as a function of NC size and oxidation degree. The comparison with experimental results shows a nice matching of the spectra, also without any tuning of the parameters. Finally, the possibility of adapting the model in order to reproduce the experimental data is explored and discussed.

Luminescent silicon nanocrystals produced by near-infrared nanosecond pulsed laser ablation in water

“…A single Si-NC, probed by confocal microscopy [26], emits, in fact, a PL with FWHM of ∼0.16 eV. The emission lineshape from an ensemble of Si-NCs has been also calculated in a recent work [27]; the reported results support the dependence of the emission broadening on the size distribution. As reported in Fig.…”

Ge–Si and Si–Ge core–shell nanocrystals: Theoretical study

“…The pure Si NC has two considerable peaks at 2.99 (414.66 nm) and 3.7 eV (355.09 nm) which are related to the vertical transition between HOMO → LUMO (%48) and HOMO-1→ LUMO+3(%31) respectively. These results are close to the previously reported experimental or theoretical data[46,47]. With growth of the Ge core radius a number of new peaks are appeared in absorption spectrum at range of 3-3.5 eV.…”

“…The experimental findings demonstrate observation of intense photoluminescence from Ge [2,6,7] and Si [8] NCs. Also some theoretical works concentrated on the accurate estimation of the optical gap for given NCs with different sizes and doping configurations [9][10][11][12][13][14][15].…”

Ultra-low reflectivity polycrystalline silicon surfaces formed by surface structure chemical transfer method

“…8 and 10) and hydrogen-terminated nanocrystalline Si. 11 Therefore, it is highly probable that the PL peak arises from band-to-band transition for nanocrystalline Si whose band-gap is widen due to the quantum-size effect. 14 On the other hand, there is a possibility that the layer consists of nanocrystalline and amorphous phases, in analogy to the previous literature.…”