Electrical transport mechanisms in ensembles of silicon quantum dots

Balberg, I.

doi:10.1002/pssc.200780103

Cited by 9 publications

(16 citation statements)

References 34 publications

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“…I-V characteristics [7,8,11,18] as we have shown both in the lateral [ Fig. 3(b)] and in the vertical [ Fig.…”

Section: Research Lettermentioning

confidence: 66%

“…However, the same potential barrier that underlies quantum confinement also limits extraction of free carriers from the confined environment and even when they are extracted, the carriers typically have to tunnel through a dielectric medium resulting in a very inefficient current flow. [9][10][11][12] Nanowires are almost perfect light-trapping materials owing to their high surface area. They are basically single-crystal materials for which the current flows easily only along the wire.…”

mentioning

confidence: 99%

“…They are basically single-crystal materials for which the current flows easily only along the wire. [10,11,13] However, individual nanowires have to be assembled with high precision to achieve a reasonable conductivity, which is still a big concern. [11,13] Random network topology, on the other hand, preserves quantum confinement properties of these two low-dimensional materials while transporting charge carriers within these physically touching, coalescing nanocrystals without the need for them to tunnel through the dielectric matrix.…”

mentioning

confidence: 99%

“…[10,11,13] However, individual nanowires have to be assembled with high precision to achieve a reasonable conductivity, which is still a big concern. [11,13] Random network topology, on the other hand, preserves quantum confinement properties of these two low-dimensional materials while transporting charge carriers within these physically touching, coalescing nanocrystals without the need for them to tunnel through the dielectric matrix. [3] Recently, QD nanowire superlattices have been reported for different material systems, [14][15][16][17] where the fabrication is usually a two-step process.…”

mentioning

confidence: 99%

“…Being isolated and located close enough to the fully connected network, these individual and/or clusters of QDs can exhibit Coulomb blockade, which is an effect of the charge quantization that is caused by sequential (non-coherent) tunneling through a small system. [7,8,11,18] To scrutinize this effect, we have compared I-V measurements of the network structure to that of the post-network structure, where the structure became bulk-like crystalline due to the enlarged sizes of the nanostructures. The subtle, but clear evidence for the Coulomb blockade gap is observed at small bias voltages through the "non-linear" …”

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confidence: 99%

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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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“…I-V characteristics [7,8,11,18] as we have shown both in the lateral [ Fig. 3(b)] and in the vertical [ Fig.…”

Section: Research Lettermentioning

confidence: 66%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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

İlday

2017

MRS Communications

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Electrical Transport Mechanisms in Ensembles of Silicon Nanocystallites

Balberg

2010

Silicon Nanocrystals

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While the optical [1][2][3] properties of various ensembles of individual Si nanocrystallites (NCs) and the memory-charge storage (CS) characteristics of two-dimensional (2D) arrays of Si NCs [4] have been investigated by many researchers, relatively little attention was paid to the transport properties of 3D ensembles of such quantum dots (QDs) [5]. The interest in the last systems, however, is expected to follow the new basic physics that it reveals and the potential applications of such systems. Following the reasonable (though still controversial [6]) understanding of granular metals [7,8], where the electrical conduction takes place via metallic particles, additional significant insights into the transport mechanism [5,9] and new phenomena are expected in Si NCs due to the presence of confined levels [10]. In particular, the combination of Coulomb blockade (CB) effects and the quantum confinement (QC) restrictions can yield various resonant tunneling effects [11] as well as various quantum phase transformations [12] that are beyond the scope of this chapter. From the application point of view, one realizes that significant electroluminescence (EL) can come about only as a result of efficient transport in 3D ensembles of Si NCs [4,13,14] that are dense enough to yield strong light emission. Finding the conditions for the optimization of the luminescence and the transport is then the route to achieve efficient Si-based photoelectronic devices [15].In this chapter, we present a review on the electrical transport in the ensembles of Si NCs. Since we are concerned with the transport in 3D ensembles of quantum dots, we will only briefly review the main results obtained from lower dimensional ensembles (i.e., 1D-like [16, 17] or perpendicular to 2D arrays [18][19][20][21]) of Si QDs in order to provide a reference for the effects of the small size of the single Si NCs on the transport in ensembles of larger dimensions. We will see that in spite of many studies of these 0D-like and 2D systems, which are essentially associated with single isolated NCs, and their potential use as nonvolatile memories, only the basics of the Silicon Nanocrystals: Fundamentals, Synthesis and Applications. Edited by Lorenzo Pavesi and Rasit Turan

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Poly(vinyl-pyrrolidone) assisted hydrothermal synthesis of flower-like CdS nanorings

Gao

Zhang

et al. 2012

Polym. Bull.

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Well-defined CdS nanorings with flower-like morphology were synthesized by a hydrothermal method using poly(vinyl-pyrrolidone) as capping agent. The phase composition, morphology, structure, and optical properties of CdS nanorings were characterized by X-ray diffraction (XRD), scanning electron microscope, transmission electron microscopy, and UV-vis absorption spectroscopic techniques. The XRD pattern of the sample can be indexed to the cubic zinc blende phase CdS. According to the quantitative analysis of energy-dispersive spectrum, the Cd:S molar ratio of the sample is about 1:0.96. The possible formation mechanism of the CdS nanorings is proposed which is based on time-resolved experiments. Furthermore, the absorption peak of CdS nanorings is red-shifted to 523 nm in the UV-vis absorption spectrum.

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Electrical transport mechanisms in ensembles of silicon quantum dots

Cited by 9 publications

References 34 publications

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

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

Electrical Transport Mechanisms in Ensembles of Silicon Nanocystallites

Poly(vinyl-pyrrolidone) assisted hydrothermal synthesis of flower-like CdS nanorings

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