Fine structure and selection rules for excitonic transitions in silicon nanostructures

Dovrat, M.; Shalibo, Yoni; Arad, N.; Popov, Inna; Lee, S.-T.; Sa’ar, A.

doi:10.1103/physrevb.79.125306

Cited by 16 publications

(19 citation statements)

References 45 publications

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“…As suggested by Dovrat et al, this leads to some further adjustment of the fine structure model discussed in Ref. [22]. The principal results shown here, however, remain correct.…”

Section: Recombination Dynamicscontrasting

confidence: 43%

Optical Properties of Silicon Nanoparticles

Meier

Lorke

2012

Nanoparticles From the Gasphase

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This chapter reviews recent results on optical spectroscopy on silicon nanoparticles. The quantum confinement effect causing a spectral shift of the photoluminescence together with an intensity enhancement is discussed. The small spatial dimensions lead not only to a change of the electronic states, but affect also the vibronic spectrum as is seen in results on first-and second-order Raman scattering. Using time-resolved spectroscopy, the excitonic fine structure of silicon nanoparticles is investigated and a crossover of bright and dark exciton states is found. The analysis of the recombination dynamics allows to determine the size-dependence of the oscillator strength, which is in the order of 10 −5 and increases with decreasing particle size. Finally, we demonstrate an electroluminescence device based on silicon particles using impact ionization. IntroductionDue to the fact that most physical, chemical, and mechanical properties of nanostructured materials are determined by their structure, especially by geometry and size, many applications have been developed based on fundamental research in this field. The reasons for the novel effects in such nanomaterials are manifold, ranging from surface effects, e.g., in nanoparticle based gas sensors, to quantum confinement effects in sufficiently small structures. Among the inorganic materials used

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“…As suggested by Dovrat et al, this leads to some further adjustment of the fine structure model discussed in Ref. [22]. The principal results shown here, however, remain correct.…”

Section: Recombination Dynamicscontrasting

confidence: 43%

Optical Properties of Silicon Nanoparticles

Meier

Lorke

2012

Nanoparticles From the Gasphase

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“…The strong fluctuations of the electronic gap with the nanocrystal size could be responsible for the large broadening of the PL spectra that have been observed experimentally, also at low temperatures. 3,5,6,8,9,12,[43][44][45][46][47][48][49] …”

Section: Discussionmentioning

confidence: 99%

“…These considerations suggest a final picture in which the gap of small embedded NCs show an oscillating behaviour with size, and not strictly following the QC, as already observed in other works. 34,38 The large broadening of the PL spectra, observed also at low temperatures, 3,5,6,8,9,12,[43][44][45][46][47][48] even for apparently monodispersed multilayered samples, 49 could be a possible consequence of such fluctuations of the electronic gap with the NC size.…”

Section: Oxidation and Strainmentioning

confidence: 99%

Size, oxidation, and strain in smallSi/SiO2nanocrystals

2009

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The structural, electronic and optical properties of Si nanocrystals of different size and shape, passivated with hydrogens, OH groups, or embedded in a SiO2 matrix are studied. The comparison between the embedded and free, suspended nanocrystals shows that the silica matrix produces a strain on the embedded NCs, that contributes to determine the band gap value. By including the strain on the hydroxided nanocrystals we are able to reproduce the electronic and optical properties of the full Si/SiO2 systems. Moreover we found that, while the quantum confinement dominates in the hydrogenated nanocrystals of all sizes, the behaviour of hydroxided and embedded nanocrystals strongly depends on the interface oxidation degree, in particular for diameters below 2 nm. Here, the proportion of NC atoms at the Si/SiO2 interface becomes relevant, producing surface-related states that may affect the quantum confinement appearing as inner band gap states and then drastically changing the optical response of the system.

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“…15 As to scale (ii) and (iii), available photoluminescence spectra for Si nanowires show a complicated profile with relatively weak intensity compared to porous Si, broad peaks (the narrowest reported linewidth ν ∼ 85 meV at 7 K), 21 and long carrier decay time on the order of 1-10 3 µs. 20,34 These properties are strongly dependent on the wire size, morphology and surface passivation. 14,19,22,23 In this situation theoretical studies on excitonic properties of Si wires were usually compared to experimental results for porous Si, 29,30 which has a yet poorly understood morphology and interface.…”

Section: 33mentioning

confidence: 99%