Publisher's Note: Radiative exciton recombination and defect luminescence observed in single silicon nanocrystals [Phys. Rev. B<b>86</b>, 125302 (2012)]

Applied Surface Science

Sciortino

Messina

et al. 2014

a b s t r a c tWe report the investigation of luminescent nanoparticles produced by ns pulsed Nd:YAG laser ablation of silicon in water. Combined characterization by AFM and IR techniques proves that these nanoparticles have a mean size of ∼3 nm and a core-shell structure consisting of a Si-nanocrystal surrounded by an oxide layer. Time resolved luminescence spectra evidence visible and UV emissions; a band around 1.9 eV originates from Si-nanocrystals, while two bands centered at 2.7 eV and 4.4 eV are associated with oxygen deficient centers in the SiO 2 shell.

Section: Resultssupporting

confidence: 53%

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

Applied Surface Science

Sciortino

Messina

et al. 2014

“…On the other hand, the gaussian lineshape is consistent with the inhomogeneous broadening of a PL emitted from an ensemble of size distributed Si‐nc (). Experiments based on confocal microscopy have indeed demonstrated that, at room temperature, the single Si‐nc emits a PL with FWHM of

\sim

0.15 eV, much narrower than that measured in the present work (FWHM ranging from

\sim

0.3 to

\sim

0.4 eV). In particular, the trend of the FWHM in our samples points out that the width of size distribution increases on increasing the SiO

_{x}

thickness.…”

Section: Discussioncontrasting

confidence: 57%

Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Physica Status Solidi (b)

Spallino

Zatsepin

et al. 2014

Time‐resolved photoluminescence from Si nanocrystals produced by 1100∘C thermal annealing of SiOx/SiO2 multilayers were investigated by tunable laser excitation, achieving a detailed excitation/emission pattern in the visible and UV range. The emission lineshape is a gaussian curve inhomogenously broadened because of the size distribution of Si nanocrystals, the excitation spectrum consists of the overlap of two gaussian bands centered around 3.4 and 5.1 eV. The mapping of luminescence spectral components with the lifetime points out the energy cubic dependence of the spontaneous emission rate. These findings are interpreted on the basis of models proposed in literature that associate this luminescence with quantum confinement of excitons or interfacial Si/SiO2 defects.

“…PL spectra were excited at 4.13 eV and acquired with T W = 10 ms and T D = 1 µs, moreover, as outlined in the following paragraph, they were detected within 10 minutes since the end of PLA to limit the instability effects. In all samples it is observed a µs decaying emission centered at 1.95 ± 0.03 eV with a FWHM of 0.6 ± 0.1 eV, that is associated with the radiative recombination of QC excitons induced by band‐to‐band transition in Si–NCs . Basing on QC effect, the peak emission energy E PL depends on the average size d of Si–NCs in agreement with the phenomenological equation:

E_{P L} = E_{g}^{b u l k} + \frac{3.73}{d^{1.39}}

where

E_{g}^{b u l k} = 1.17

eV is the band energy gap of bulk Si crystal at room temperature.…”

Section: Resultssupporting

confidence: 90%

Luminescence Efficiency of Si/SiO₂ Nanoparticles Produced by Laser Ablation

Cannas

Camarda

Physica Status Solidi (a)

et al. 2019

Photoluminescence properties of Si(core)/SiO2(shell) nanoparticles produced by pulsed laser ablation in aqueous solution are investigated with the purpose to highlight the microscopic processes that govern the emission brightness and stability. Time resolved spectra evidence that these systems emit a µs decaying band centered around 1.95 eV, that is associated with the radiative recombination of quantum‐confined excitons generated in the Si nanocrystalline core. Both the quantum efficiency and the stability of this emission are strongly dependent on the pH level of the solution, that is changed after the laser ablation is performed. They enhance in acid environment because of the H+ passivation of non radiative defects, located in the Si/SiO2 interface, which causes the growth of IR‐active SiH groups. On the basis of the reported experimental results and previous literature data, we propose that the non radiative defects are located in the suboxide interlayer between Si and SiO2 and their nature is affected by the latter.