Correlation between luminescence and structural properties of Si nanocrystals

Iacona, Fabio; Franzò, G.; Spinella, C.

doi:10.1063/1.372013

Cited by 510 publications

(373 citation statements)

References 44 publications

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“…A technologically important structure, which is fully complementary metal-oxide semiconductor ͑CMOS͒ compatible and takes advantage of the well-known good passivation and stability of the Si/ SiO 2 interface, consists of crystalline silicon nanoclusters ͑Si-ncl͒ dispersed in an amorphous SiO 2 matrix. 1,2 The mechanisms of light emission in these structures have been studied intensively. Time-resolved photoluminescence ͑PL͒ measurements have shown a nonexponential PL intensity decay in the microsecond range that can be fit by the stretched-exponential function I͑t͒ =I 0 exp͓−͑t / ͒ ␤ ͔, where I 0 is the initial PL intensity, is a lifetime, and ␤ Յ 1 is a dispersion exponent.…”

Section: Introductionmentioning

confidence: 99%

The role of quantum confinement and crystalline structure on excitonic lifetimes in silicon nanoclusters

Borrero-González

Nunes

Andreeta

et al. 2010

Journal of Applied Physics

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Temperature dependent photoluminescence from porous silicon nanostructures: Quantum confinement and oxide related transitions J. Appl. Phys. 110, 094309 (2011) Photoluminescence of deep defects involving transition metals in Si: New insights from highly enriched 28Si App. Phys. Rev. 2011, 15 (2011 Photoluminescence of deep defects involving transition metals in Si: New insights from highly enriched 28Si J. Appl. Phys. 110, 081301 (2011) Dielectric effects on the optical properties of single silicon nanocrystals J. Appl. Phys. 110, 074312 (2011) Photoluminescence origins of the porous silicon nanowire arrays J. Appl. Phys. 110, 073109 (2011) Additional information on J. Appl. Phys. The emission energy dependence of the photoluminescence ͑PL͒ decay rate at room temperature has been studied in Si nanoclusters ͑Si-ncl͒ embedded in Si oxide matrices obtained by thermal annealing of substoichiometric Si oxide layers Si y O 1−y , y=͑0.36, 0.39, 0.42͒, at various annealing temperatures ͑T a ͒ and gas atmospheres. Raman scattering measurements give evidence for the formation of amorphous Si-ncl at T a = 900°C and of crystalline Si-ncl for T a = 1000°C and 1100°C. For T a = 1100°C, the energy dispersion of the PL decay rate does not depend on sample fabrication conditions and follows previously reported behavior. For lower T a , the rate becomes dependent on fabrication conditions and less energy dispersive. The effects are attributed to exciton localization and decoherence leading to the suppression of quantum confinement and the enhancement of nonradiative recombination in disordered and amorphous Si-ncl.

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Section: Introductionmentioning

confidence: 99%

The role of quantum confinement and crystalline structure on excitonic lifetimes in silicon nanoclusters

Borrero-González

Nunes

Andreeta

et al. 2010

Journal of Applied Physics

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“…Recently the subject of wide bandgap oxides and nitrides have gained interest within the context of nanocrystals which offer silicon-based technology for light emitting devices and semiconductor memories 3 . These nanocrystals are embedded in an insulating matrix which is usually chosen to be silica 4,5,6,7 . However, other wide bandgap materials are also employed such as germania 8,9 , silicon nitride 10,11,12 , and alumina 13,14,15 .…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the insulating oxides and nitrides: SiO2, GeO2, Al2O3, Si3N4, and Ge3N4

Sevik

Bulutay

2007

J Mater Sci

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An extensive theoretical study is performed for wide bandgap crystalline oxides and nitrides, namely, SiO2, GeO2, Al 2O3, Si3N4, and Ge3N 4. Their important polymorphs are considered which are for SiO 2: α-quartz, α- and β-cristobalite and stishovite, for GeO2: α-quartz, and rutile, for Al2O 3: α-phase, for Si3N4 and Ge 3N4: α- and β-phases. This work constitutes a comprehensive account of both electronic structure and the elastic properties of these important insulating oxides and nitrides obtained with high accuracy based on density functional theory within the local density approximation. Two different norm-conserving ab initio pseudopotentials have been tested which agree in all respects with the only exception arising for the elastic properties of rutile GeO2. The agreement with experimental values, when available, are seen to be highly satisfactory. The uniformity and the well convergence of this approach enables an unbiased assessment of important physical parameters within each material and among different insulating oxide and nitrides. The computed static electric susceptibilities are observed to display a strong correlation with their mass densities. There is a marked discrepancy between the considered oxides and nitrides with the latter having sudden increase of density of states away from the respective band edges. This is expected to give rise to excessive carrier scattering which can practically preclude bulk impact ionization process in Si3N4 and Ge3N4. © Springer Science+Business Media, LLC 2007

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“…2,3 The spectral shapes are very similar, even though their full width at half maximum is narrower ͑close to ϳ90 nm, i.e., ϳ0.190 eV͒ than the one obtained in similar samples under optical pumping. 16 This can be attributed to interference effects caused by multiple reflections in the poly-Si layer, as revealed by transmittance measurements ͑figure not shown͒. The small peak shift is attributed to the different refractive index contrast at the poly-Si/insulator interface that modifies the interference pattern of the stack.…”

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Efficiency and reliability enhancement of silicon nanocrystal field-effect luminescence from nitride-oxide gate stacks

Perálvarez

Carreras

Barreto

et al. 2008

Applied Physics Letters

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We report on a field-effect light emitting device based on silicon nanocrystals in silicon oxide deposited by plasma-enhanced chemical vapor deposition. The device shows high power efficiency and long lifetime. The power efficiency is enhanced up to ϳ0.1% by the presence of a silicon nitride control layer. The leakage current reduction induced by this nitride buffer effectively increases the power efficiency two orders of magnitude with regard to similarly processed devices with solely oxide. In addition, the nitride cools down the electrons that reach the polycrystalline silicon gate lowering the formation of defects, which significantly reduces the device degradation. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2939562͔The materials based on silicon nanocrystals ͑Si-ncs͒ are attractive for a wide variety of electronic and optoelectronic applications thanks to their tunable emission in the visible range and their compatibility with mainstream complementary metal oxide semiconductor ͑MOS͒ technology. [1][2][3][4][5][6] In the last years, an increasing number of articles dealing with electroluminescence ͑EL͒ from Si-nc embedded in silicon oxide ͑Si-nc/ SiO 2 ͒ devices has been published. Many of them report emission under direct current ͑dc͒ polarization, 7-9 which usually leads to low emission efficiency and fast degradation. Other authors report emission under alternate current ͑ac͒ polarization, 3,10,11 applying the concept of field-effect luminescence, where the recombination takes place after the sequential injection from the substrate of electrons and holes. The alternate injection can be adjusted to a suitable duty cycle which optimizes not only the current flow but also the polarization stress and the device lifetime. In spite of this, the leakage current is still very high and, also in this case, leads to low power efficiencies. 10 Therefore, the reduction of the leakage current appears to be a key issue for the achievement of an efficient device. In this challenge, the addition of a thin silicon nitride ͑Si 3 N 4 ͒ layer in a typical metal nitrideoxide semiconductor ͑MNOS͒ configuration is presented as a promising solution. [12][13][14] The MNOS stack reduces the effective field in the oxide layer, lowering the current flow that, in MOS configurations, is strongly field dependent ͓Fowler-Nordheim ͑FN͔͒. 15 The additional nitride barrier hinders the gate injection without significantly affecting the injection from the substrate, thus enhancing the power efficiency, as will be demonstrated later on. Thanks to the thinness of the Si 3 N 4 buffer and to its relatively high dielectric constant, the overall thickness increase does not have a remarkable impact on the gate voltage. The device lifetime improves as the nitride matrix cools down the carriers from the oxide, reducing the damage generated at the polycrystalline silicon ͑top contact͒ interface.In the present work, we demonstrate a twofold improvement through the addition of a thin Si 3 N 4 control layer within the MOS stack. First, we show ...

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Correlation between luminescence and structural properties of Si nanocrystals

Cited by 510 publications

References 44 publications

The role of quantum confinement and crystalline structure on excitonic lifetimes in silicon nanoclusters

The role of quantum confinement and crystalline structure on excitonic lifetimes in silicon nanoclusters

Theoretical study of the insulating oxides and nitrides: SiO2, GeO2, Al2O3, Si3N4, and Ge3N4

Efficiency and reliability enhancement of silicon nanocrystal field-effect luminescence from nitride-oxide gate stacks

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