Superlinear photoluminescence in silicon nanocrystals: The role of excitation wavelength

Trojánek, F.; Žídek, Karel; Neudert, K.; Pelant, I.; Malý, P.

doi:10.1016/j.jlumin.2006.08.003

Cited by 6 publications

(5 citation statements)

References 14 publications

(20 reference statements)

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“…Interestingly, the up-converted emission was shown to be identical to the typical photoluminescence spectrum. Very weak up-converted emission has also been reported with O : SiQDs [198,279].…”

Section: Absorption Cross-sectionmentioning

confidence: 82%

“…In such a case, however, size distribution, size-dependence of radiative rates, absorption cross-section and optical bandgap must be properly taken into account. Furthermore, the presence of ultrafast quenching mechanisms, such as surface trapping, and the size-dependence of radiative and nonradiative recombination rates, makes emission spectra also strongly dependent on the modes of excitation (continuous wave/pulse duration) and detection [32,197,198].…”

Section: Optical Bandgap Spectral Tunabilitymentioning

confidence: 99%

“…Besides, the kinetics of carriers is strongly influenced by ultrafast carrier trapping at surface-related levels [197,198] and the possible formation of a self-trapped exciton [176]. The ultrafast surface-related trapping of carriers in O : SiQDs critically limits emission efficiency, as the radiative recombination is incomparably slow.…”

Section: Radiative Rate and Emission Efficiencymentioning

confidence: 99%

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Silicon quantum dots: surface matters

Dohnalová

Gregorkiewicz

Kůsová

2014

J. Phys.: Condens. Matter

199

208

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Silicon quantum dots (SiQDs) hold great promise for many future technologies. Silicon is already at the core of photovoltaics and microelectronics, and SiQDs are capable of efficient light emission and amplification. This is crucial for the development of the next technological frontiers-silicon photonics and optoelectronics. Unlike any other quantum dots (QDs), SiQDs are made of non-toxic and abundant material, offering one of the spectrally broadest emission tunabilities accessible with semiconductor QDs and allowing for tailored radiative rates over many orders of magnitude. This extraordinary flexibility of optical properties is achieved via a combination of the spatial confinement of carriers and the strong influence of surface chemistry. The complex physics of this material, which is still being unraveled, leads to new effects, opening up new opportunities for applications. In this review we summarize the latest progress in this fascinating research field, with special attention given to surface-induced effects, such as the emergence of direct bandgap transitions, and collective effects in densely packed QDs, such as space separated quantum cutting.

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Section: Absorption Cross-sectionmentioning

confidence: 82%

Section: Optical Bandgap Spectral Tunabilitymentioning

confidence: 99%

Section: Radiative Rate and Emission Efficiencymentioning

confidence: 99%

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Silicon quantum dots: surface matters

Dohnalová

Gregorkiewicz

Kůsová

2014

J. Phys.: Condens. Matter

199

208

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“…It has been widely observed that the PL relaxation of carrier-confined Si ensembles exhibits a multiexponential or typically stretched-exponential form. [6][7][8][9][10][11][12][13][14][15][16][17] Such observations are a source of anomaly as populations of confined carrier densities emitting at a given energy are expected to ideally share a single recombination rate and thus decay according to a single exponential. 18 Multiexponential curves on the other hand imply either recombination rate dispersions or a recombination rate that is time varying.…”

Section: Introductionmentioning

confidence: 99%

Multiexponential photoluminescence decay of blinking nanocrystal ensembles

et al. 2009

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We investigate the relationship between the multiexponential photoluminescence ͑PL͒ dynamics of large nanocrystal ͑NC͒ ensembles and the intensity intermittency ͑blinking͒ characteristic of single NCs. A general model is developed and a simple fitting form derived for the analysis of PL decay curves allowing the extraction of both the intrinsic radiative recombination rate and an intensity intermittence parameter. The analysis is applied to the PL of a series of Si-NCs embedded in silicon oxide matrices yielding a good agreement between extracted and theoretical recombination rates. An excellent agreement is furthermore reported between the range of power-law exponents obtained and those previously determined through both single-NC experiments and current blinking mechanism theory. We suggest that a similar approach may well be fruitful in the analysis of time-resolved PL for a large variety of other carrier-confined materials.

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“…In the optical domain, such nonlinear responses require a saturable optical transition, which can be an intrinsic optical property of the target object, or the result of a spatially modulated saturation as implemented in STED (stimulated emission depletion) microscopy 6 . While such intrinsically nonlinear responses have been characterized for a range of photo-luminescent semiconductor objects, such as quantum dots 7 or Si nanoparticles 8 , molecular fluorophores have also been successfully engineered for enhancing nonlinearities, leading to different methods of super-resolution microscopy 9 . However, beyond the context of photo-luminescence and super-resolved optical microscopy, the detection of any kind of object by its response to an electromagnetic excitation requires that a significant part of the excitation energy be scattered or converted into some sort of detectable radiative response.…”

Section: Introductionmentioning

confidence: 99%

Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation

Graciani

Amblard

2019

Nat Commun

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Blackbody radiation is a fundamental phenomenon in nature, and its explanation by Planck marks a cornerstone in the history of Physics. In this theoretical work, we show that the spectral radiance given by Planck’s law is strongly superlinear with temperature, with an arbitrarily large local exponent for decreasing wavelengths. From that scaling analysis, we propose a new concept of super-resolved detection and imaging: if a focused beam of energy is scanned over an object that absorbs and linearly converts that energy into heat, a highly nonlinear thermal radiation response is generated, and its point spread function can be made arbitrarily smaller than the excitation beam focus. Based on a few practical scenarios, we propose to extend the notion of super-resolution beyond its current niche in microscopy to various kinds of excitation beams, a wide range of spatial scales, and a broader diversity of target objects.

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Superlinear photoluminescence in silicon nanocrystals: The role of excitation wavelength

Cited by 6 publications

References 14 publications

Silicon quantum dots: surface matters

Silicon quantum dots: surface matters

Multiexponential photoluminescence decay of blinking nanocrystal ensembles

Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation

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