Fundamental transport processes in ensembles of silicon quantum dots

Balberg, I.; Savir, E.; Jędrzejewski, J.; Nassiopoulou, A. G.; Gardelis, S.

doi:10.1103/physrevb.75.235329

Cited by 55 publications

(90 citation statements)

References 66 publications

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“…Actually, the Raman analysis described in section 3.1 provides consistence to the hypothesis of a larger number of NCs while preserving the mean NC crystalline size, which induces a shorter inter-NC distance and possibly causes Si coalescence. In fact, Si NC lateral coalescence at high Si content (above the percolation threshold) was reported in [16] in similar SL systems, producing the carrier wavefunction delocalization within the nanostructures and subsequent coupling of the electronic states. Due to the shorter inter-NC distance supported by the structural characterization, this effect might also take place in our devices, resulting in the relaxation of the quantum confinement effect, as observed in the past in III-V semiconductor quantum wells [24][25][26].…”

Section: Electrical and El Characterizationmentioning

confidence: 99%

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: Electrical and El Characterizationmentioning

confidence: 99%

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 heavily boron doped films, conductivity values of about 0.1 (Ohm cm) -1 were reported by Mirabella et al (Mirabella et al, 2010). However as shown in (Balberg et al, 2007) in this high Si-excess regime (above the percolation threshold) the photoluminescence observed for isolated Si-QDs is absent due to the growth of the cluster size and hence relaxation of the quantum confinement effect. For this reason this clustered structures seem less favorable for many of the illustrated application of Si-QDs reviewed here.…”

Section: Electrical Transport Propertiesmentioning

confidence: 85%

“…For this reason this clustered structures seem less favorable for many of the illustrated application of Si-QDs reviewed here. Conductivity in SiO 2 films with isolated Si-QDs is in the order of 10 -10 (Ohm cm) -1 (Balberg et al 2007). In recent years films representing this type of structure were intensively investigated especially for realization of silicon base light emitting devices (Perálvarez et al, 2006;Franzò et al, 2002;Prezioso et al, 2008) and references therein.…”

Section: Electrical Transport Propertiesmentioning

confidence: 99%

“…The conduction mechanism in dielectric matrices containing Si-QDs depends strongly on the type of matrix (silicon dioxide, silicon-nitride and silicon carbide are the most commons one) and on the distance between the Si-QDs. When Si-QDs are prepared by phase separation from silicon rich oxide two distinct regions can be found in conductivity measurements: a region in which the content of excess silicon is so large that the Si-QDs are not isolated anymore but form a percolation backbone and a lower Si-excess region in which the Si-QDs are isolated and conductivity is dominated by tunneling processes (Balberg et al, 2007). In the region of large Si-excess the conductivity is in the order of 10 -7 (Ohm cm) -1 , which is about 3 orders of magnitude lower than the conductivity of high resistivity floating zone silicon (~10 -4 (Ohm cm) -1 ).…”

Section: Electrical Transport Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Silicon Quantum Dots for Photovoltaics: A Review

Pucker¹,

Serra²,

Jestin³

2012

Quantum Dots - A Variety of New Applications

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“…Our findings strongly suggest that, when optimized, these structures can be a strong candidate for use in photovoltaic device applications. Further, by slightly modifying the topology, we were able to create isolated QD clusters that effectively formed a double-barrier tunneling junction (DBTJ) [6][7][8] that could store charges. The anisotropic random network is prepared as a thin film in a magnetron-sputtered physical vapor deposition chamber, the details of the fabrication procedure and characterization methods can be found in the Supplementary document.…”

mentioning

confidence: 99%

Strongly scale-dependent charge transport from interconnections of silicon quantum dots and nanowires

İlday

2017

MRS Communications

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We present the first characterization of strongly scale-dependent charge transport of a unique, hierarchical complex topology: an interconnected random network of silicon quantum dots (QDs) and nanowires. We show that this specific topology has different charge transport characteristics on the nanoscale and the microscale: photogenerated charge carriers tend to be confined inside the QDs and externally injected charge carriers flow preferably along the nanowires. The former enables expression of quantum confinement properties, and the latter mainly contributes to the good electrical conduction on the microscale. Our findings strongly suggest that this multifunctionality can be controlled and used in photovoltaic device applications.Hierarchical materials that can perform seemingly contradicting tasks at multiple length scales are omnipresent in Nature such as strong but tough bone structure, confined but connected brain cells or strong but light spider silk. [1,2] However, humanmade systems are yet to demonstrate such multifunctionality at multiple length scales.[1] The attention so far has been given to the investigation and understanding of nanomaterials, and only recently we have started to explore the interconnections of these low-dimensional materials. [3][4][5] We now know that shape and size of the nanomaterials significantly alter their optical, electrical, magnetic, and structural properties; however, there is a whole new paradigm when they organize hierarchically and interconnect in such a way to form multiscale topologies. [3,5] If designed carefully, such multiscale topologies could have significant implications for nanotechnology by operating at vastly different length scales from nano to macro. Needless to say, the potential use of these complex structures with topology-dependent features in many applications rely on our ability to understand and control the electronic, optical, magnetic, and chemical interactions between the individual nanostructures along with our capability to exploit their collective properties. However, not only the demonstrations of such complex topologies are very rare, but also their scale-dependent features are poorly understood.Recently, we have demonstrated such a multiscale, hierarchical complex structure, an anisotropic random network of silicon quantum dots (QDs), to be potentially used in solar cells. [3] Therefore, the topology was designed to be isotropic on the nanoscale (up to ∼10 nm) to preserve tunable band gap feature of the QDs in the visible light range (from ∼1.8 to 2.7 eV) and anisotropic on the microscale (over tens to hundreds of nanometers) to electrically percolate these dots (conductivity of ∼0.1 S/m) and form heavily undulated and branching nanowire-like structures. Here, we show that this structure has different charge transport characteristics on the nanoscale and on the microscale owing to its unique topology for the charges that are locally generated through the photoelectric effect and for those that are injected externally through the e...

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Fundamental transport processes in ensembles of silicon quantum dots

Cited by 55 publications

References 66 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

Silicon Quantum Dots for Photovoltaics: A Review

Strongly scale-dependent charge transport from interconnections of silicon quantum dots and nanowires

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Fundamental transport processes in ensembles of silicon quantum dots

Cited by 55 publications

References 66 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

Silicon Quantum Dots for Photovoltaics: A Review

Strongly scale-dependent charge transport from interconnections of silicon quantum dots and nanowires

Contact Info

Product

Resources

About

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