Photoactivation of silicon quantum dots

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.

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“…13-14, and I(E g ) from Eqs. [16][17]. Finally, the sum over the N G(E) has been performed, forming the emission spectrum (i.e.…”

Section: Emissionmentioning

confidence: 99%

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

Guerra

Cigarini

Ossicini

2013

Journal of Applied Physics

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“…Precipitation of excess Si in SiO 2 typically requires temperatures in the range 1000-1100 ∘ C for 1 h and produces Si-NCs with diameters between 3 to 7 nm [1,2]. Si-NCs exhibit a strong room temperature photoluminescence (PL) as a direct consequence of their small size, but nonradiative surface defects, as P b defect, compete with radiative process [3][4][5][6]. SiO 2 is an appropriate matrix for Si-NCs since it can passivate some dangling bonds that can cause nonradiative transitions.…”

Section: Introductionmentioning

confidence: 99%

“…However, a better control of surface defects on Si-NCs is valuable for light-emitting applications [3,6,7]. Annealing in molecular hydrogen can reduce the high concentration of surface defects, and then luminescence intensity from Si-NCs signi�catively increases [2][3][4][5][6][7][8]. It has been reported that a sample containing Si-NCs and passivated at 510 ∘ C in molecular hydrogen can increase its photoluminescence signal by a factor of seven [4].…”

Section: Introductionmentioning

confidence: 99%

Improving Passivation Process of Si Nanocrystals Embedded in SiO₂Using Metal Ion Implantation

Bornacelli

Fernández

Oliver

2013

Journal of Nanotechnology

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We studied the photoluminescence (PL) of Si nanocrystals (Si-NCs) embedded in SiO2obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm) inside the SiO2achieving a robust and better protected system. After metal ion implantation (Ag or Au), and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs) could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO2matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H2/N2and Ar) to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

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“…As it is shown there, PL lifetime has increased in the sample with metal ion implantation. As mentioned in other works, this could be related to improving surface defects passivation on Si-NCs [4,7,[10][11][12][13]. Hydrogen depth profile of the sample with Ag implantation and its reference without it are shown in Figure 4(b).…”

Section: Resultsmentioning

confidence: 56%

“…The Pb defects, or dangling bonds, are known to cause quenching of the PL from Si-NCs [4][5][6]. Much research has been done to find a method to enhance the PL emission from a system of Si-NCs in SiO 2 by controlling the passivation of their surface defects by using gases such as hydrogen (H 2 ), nitrogen (N 2 ), or oxygen (O 2 ) [7][8][9][10][11][12][13][14]. It is well known that a thermal treatment in a molecular hydrogen-containing atmosphere increases the PL from Si-NCs more than Nitrogen or Oxygen [7].…”

Section: Introductionmentioning

confidence: 99%

Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

Bornacelli

Reyes‐Esqueda

Rodrı́guez-Fernández

et al. 2014

Journal of Nanotechnology

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Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs) have become the main building block of silicon photonic (modulators, waveguide, source, and detectors). In this work, we present an approach based on implantation of Ag (or Au) ions and a proper thermal annealing in order to improve the photoluminescence (PL) emission of Si-NCs embedded in SiO 2 . The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 m under surface). Once Si-NCs are formed inside the SiO 2 we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs.

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Photoactivation of silicon quantum dots

Cited by 19 publications

References 43 publications

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

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

Improving Passivation Process of Si Nanocrystals Embedded in SiO₂Using Metal Ion Implantation

Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

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Photoactivation of silicon quantum dots

Cited by 19 publications

References 43 publications

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

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

Improving Passivation Process of Si Nanocrystals Embedded in SiO2Using Metal Ion Implantation

Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

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Improving Passivation Process of Si Nanocrystals Embedded in SiO₂Using Metal Ion Implantation