Evolution of the optical properties of Si nanoparticles embedded in SiO2 as function of annealing conditions

Stenger, Ingrid; Gallas, Bruno; Siozade, Laure; Kao, C.-C.; Chénot, Stéphane; Fisson, S.; Vuye, G.; Rivory, J.

doi:10.1063/1.2937086

Cited by 21 publications

(10 citation statements)

References 37 publications

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“…The above results can explain experimental observations, that a phase change from amorphous to crystalline nanoparticles is observed at annealing T ∼ 1150 • C [19,20,21,22,23,24]. This explanation is based on the experimental observation that the size of nanoparticles grow with T [24].…”

Section: Disorder/order Phase Transition In Si Nanoparticlessupporting

confidence: 57%

Nucleation of silicon nanoparticles in amorphous silicon dioxide matrices

Meloni¹

2014

AIP Conference Proceedings

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In this contribution I summarize our research on the formation of nanoparticles embedded in a-SiO 2 − x matrices. In particular, I focus on the Si diffusion in SiO 2−x matrices, and amorphous-to-crystalline phase transition in Si nanoparticles embedded in SiO 2−x .I show that Si diffusion can be rationalized in terms of three mechanisms: O-driven (i.e. driven by the change of Ocoordination), Si-driven, and bond-swapping (i.e. driven by the change of "local" stoichiometry). The relevance of each of these mechanisms depends on the silicon concentration in the sample and on the temperature. The O-driven mechanism dominates at low Si concentrations, and Si-driven and bond-swapping dominate at higher ones. At higher T the effect is mitigating the difference of contribution among the various mechanisms.Concerning amorphous-to-crystalline phase transition, I show that in small nanoparticles (radius ≤ 2 nm) the more stable phase at low T s is the amorphous one, i.e. there is an inversion of the relative stability between the two phases with respect to bulk systems. In larger nanoparticles the bulk-like behavior is recovered. High temperatures favors the crystal phase in small nanoparticles. These results can explain the experimental observations that nanoparticles undergo to a phase transition in preparation protocol adopting "high" annealing temperatures (T ≥ 1150 • C).

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Section: Disorder/order Phase Transition In Si Nanoparticlessupporting

confidence: 57%

Nucleation of silicon nanoparticles in amorphous silicon dioxide matrices

Meloni¹

2014

AIP Conference Proceedings

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“…Results from Energy Filtered Transmission Electron Microscopy (EFTEM) and Dark-Field Transmission Electron Microscopy (DFTEM) on Si-rich SiO x show that Si nanoparticles start to form at 1000 • C [28,29,24,25,30,27]. At this temperature they are all amorphous, while at 1100 • C about one third become crystalline.…”

Section: Resultsmentioning

confidence: 99%

Combining Rare Events Techniques: Phase Change in Si Nanoparticles

2011

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We introduce a combined Restrained MD/Parallel Tempering approach to study the difference in free energy as a function of a set of collective variables between two states in presence of unknown slow degrees of freedom.We applied this method to study the relative stability of the amorphous vs crystalline nanoparticles of size ranging between 0.8 and 1.8 nm as a function of the temperature. We found that, at variance with bulk systems, at low T small nanoparticles are amorphous and undergo an amorphous-to-crystalline phase transition at higher T . On the contrary, large nanoparticles recover the bulk-like behavior: crystalline at low T and amorphous at high T .

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“…This assumption is in keeping with most experimental observations [15,16,[21][22][23]. Let the size distribution fulfill the above relation, and insert the probability for a discrete radius into Eq.…”

Section: Numerical Simulation and Analysismentioning

confidence: 89%

Scheme for extracting size-distribution information of a quantum dot ensemble from its absorption spectrum

2013

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We design a scheme for obtaining size distribution information for colloidal quantum dots (QDs) embedded in a host material. The calculation uses the QDs' optical absorption spectrum and requires the absorption spectra for a series of sample QDs, having a uniform size distribution with specific radii. In an analogy to a quantum state expanded by a basis vector set, the absorption spectrum of a QD ensemble with an unspecified size distribution can be expanded by those of the sample spectra, which are treated as basis vectors. The proportion of QDs with a radius around each sample's radius can be extracted. We also discuss the case without sufficient sample spectra.

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Evolution of the optical properties of Si nanoparticles embedded in SiO2 as function of annealing conditions

Cited by 21 publications

References 37 publications

Nucleation of silicon nanoparticles in amorphous silicon dioxide matrices

Nucleation of silicon nanoparticles in amorphous silicon dioxide matrices

Combining Rare Events Techniques: Phase Change in Si Nanoparticles

Scheme for extracting size-distribution information of a quantum dot ensemble from its absorption spectrum

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