Low-voltage onset of electroluminescence in nanocrystalline-Si/SiO2 multilayers

Anopchenko, Aleksei; Marconi, A.; Moser, E.; Prezioso, S.; Wang, M.; Pavesi, L.; Pucker, G.; Bellutti, P.

doi:10.1063/1.3194315

Cited by 72 publications

(57 citation statements)

References 41 publications

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“…Considering this point we have chosen the maximum η PE , provided that the corresponding current injection and applied voltage satisfied these considerations for all devices. The obtained power efficiencies in this way are summarized in figure 6, with values that span from 10 −7 to 10 −3 %, lower than other results in literature on similar samples [17,19]. In these former works, tunnel injection of carriers dominates charge transport, which results into more efficient impact ionization than in our devices (dominated by bulk-limited transport mechanisms).…”

Section: Structural Parameters Effect On the Electro-optical Conversionmentioning

confidence: 47%

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO₂ superlattices

López-Vidrier¹,

Berencén²,

Hernández³

et al. 2015

Nanotechnology

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The effect of the oxide barrier thickness (tSiO2) reduction and the Si excess ([Si]exc) increase on the electrical and electroluminescence (EL) properties of Si-rich oxynitride (SRON)/SiO2 superlattices (SLs) is investigated. The active layers of the metal–oxide–semiconductor devices were fabricated by alternated deposition of SRON and SiO2 layers on top of a Si substrate. The precipitation of the Si excess and thus formation of Si nanocrystals (NCs) within the SRON layers was achieved after an annealing treatment at 1150 °C. A structural characterization revealed a high crystalline quality of the SLs for all devices, and the evaluated NC crystalline size is in agreement with a good deposition and annealing control. We found a dramatic conductivity enhancement when the Si content is increased or the SiO2 barrier thickness is decreased, due to a larger interaction of the carrier wavefunctions from adjacent layers. EL recombination dynamics were studied, revealing radiative recombination decay times of the order of tens of microseconds. Lower lifetimes were found at higher [Si]exc, attributed to exciton confinement delocalization, whereas intermediate barrier thicknesses present the slowest decay. The electrical-to-light conversion efficiency increases monotonously at thicker barriers and smaller Si contents. We ascribe these effects mainly to free carriers, which enhance carrier transport through the SLs while strongly quenching light emission. Finally, the combination of the different results led us to conclude that tSiO2 ∼ 2 nm and [Si]exc from 12 to 15 at% are the ideal structure parameters for a balanced electro-optical response of Si NC-based SLs.

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Section: Structural Parameters Effect On the Electro-optical Conversionmentioning

confidence: 47%

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO₂ superlattices

López-Vidrier¹,

Berencén²,

Hernández³

et al. 2015

Nanotechnology

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“…For this thickness, the onset voltage is very high (>50 V). Such high voltages, favors the injection of high-energy hot electrons [39,40], which is known to induce dielectric breakdown.…”

Section: Conductivity-electroluminescence Correlationmentioning

confidence: 99%

Structural factors impacting carrier transport and electroluminescence from Si nanocluster-sensitized Er ions

Cueff¹,

Labbé²,

Jambois³

et al. 2012

Opt. Express

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Abstract:We present an analysis of factors influencing carrier transport and electroluminescence (EL) at 1.5 µm from erbium-doped silicon-rich silica (SiO x ) layers. The effects of both the active layer thickness and the Siexcess content on the electrical excitation of erbium are studied. We demonstrate that when the thickness is decreased from a few hundred to tens of nanometers the conductivity is greatly enhanced. Carrier transport is well described in all cases by a Poole-Frenkel mechanism, while the thickness-dependent current density suggests an evolution of both density and distribution of trapping states induced by Si nanoinclusions. We ascribe this observation to stress-induced effects prevailing in thin films, which inhibit the agglomeration of Si atoms, resulting in a high density of sub-nm Si inclusions that induce traps much shallower than those generated by Si nanoclusters (Si-ncs) formed in thicker films. There is no direct correlation between high conductivity and optimized EL intensity at 1.5 µm. Our results suggest that the main excitation mechanism governing the EL signal is impact excitation, which gradually becomes more efficient as film thickness increases, thanks to the increased segregation of Si-ncs, which in turn allows more efficient injection of hot electrons into the oxide matrix. Optimization of the EL signal is thus found to be a compromise between conductivity and both number and degree of segregation of Si-ncs, all of which are governed by a combination of excess Si content and sample thickness. This material study has strong implications for many electricallydriven devices using Si-ncs or Si-excess mediated EL. USSR 5, 685-687 (1938). ©2012 Optical Society of America

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“…While the SRO layer thickness influences the size of nanocrystals, the control of SiO 2 layer thickness influences the electrical-transport through the stack and can result in significant improvement in the performances of Si-nc-based light emitting diodes. [6] Another potential field of application for this type of materials is the development of solar cells with tunable band gap. [7] Within this study, we investigate the structural evolution during thermal annealing of a nominally 8 nm SiO 2 /8 nm SRO SL through different analytical methods: variable angle ellipsometric spectroscopy (VASE), SIMS, XPS and X-ray reflectivity (XRR).…”

Section: Introductionmentioning

confidence: 99%

Structural analyses of thermal annealed SRO/SiO₂ superlattices

Vanzetti¹,

Pucker²,

Milita³

et al. 2010

Surface & Interface Analysis

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Nanocrystalline silicon embedded in dielectric matrices is currently studied for Si-photonics, memory devices and solar cells. A common method for the preparation of silicon nanocrystals embedded in oxides is the phase separation of silicon rich oxide (SRO) in SiO 2 and Si via thermal annealing. Phase separation, nucleation and crystallization of SRO are known to depend on the thickness of the SRO layer. Here we investigate the structural changes in a sample consisting of alternated nanometer-thick SRO and SiO 2 layers -a so-called superlattice (SL) -during thermal annealing. Under a thermal treatment the material undergoes a series of modifications due to sintering, phase separation, crystallization and layer mixing. In this work we investigate these transformations in an SL grown by plasma enhanced chemical vapor deposition (PECVD) with several analytical techniques: XPS, variable angle ellipsometric spectroscopy (VASE), SIMS, and X-ray reflectivity (XRR). Both SIMS and XRR measurements clearly reveal the periodicity of the samples. XPS analysis reveals that phase separation of SRO in silicon and SiO 2 occurs in the annealing temperature range 600-925• C. The process is accompanied by reduction in overall thickness of the samples (ongoing also at higher temperatures) as evidenced from the ellipsometric spectra. A maximum form birefringence is achieved at 925• C and stays nearly constant until 1100• C. Eventually, the form birefringence decreases at the highest annealing temperature of 1150• C, which according to SIMS measurements is caused by a partial oxidation of silicon in the outermost SRO layer. Copyright

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Low-voltage onset of electroluminescence in nanocrystalline-Si/SiO2 multilayers

Abstract: Articles you may be interested inElectroluminescence and charge storage characteristics of quantum confined germanium nanocrystals Electrical conduction and electroluminescence in nanocrystalline silicon-based light emitting devices

Cited by 72 publications

References 41 publications

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO₂ superlattices

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO₂ superlattices

Structural factors impacting carrier transport and electroluminescence from Si nanocluster-sensitized Er ions

Structural analyses of thermal annealed SRO/SiO₂ superlattices

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Low-voltage onset of electroluminescence in nanocrystalline-Si/SiO2 multilayers

Abstract: Articles you may be interested inElectroluminescence and charge storage characteristics of quantum confined germanium nanocrystals Electrical conduction and electroluminescence in nanocrystalline silicon-based light emitting devices

Cited by 72 publications

References 41 publications

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO2 superlattices

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO2 superlattices

Structural factors impacting carrier transport and electroluminescence from Si nanocluster-sensitized Er ions

Structural analyses of thermal annealed SRO/SiO2 superlattices

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Product

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Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO₂ superlattices

Structural parameters effect on the electrical and electroluminescence properties of silicon nanocrystals/SiO₂ superlattices

Structural analyses of thermal annealed SRO/SiO₂ superlattices