Cadmium Selenide Quantum Wires and the Transition from 3D to 2D Confinement

Hua, Yu; Li, Jingbo; Loomis, Richard A.; Gibbons, P. C.; Wang, Lin‐Wang; Buhro, William E.

doi:10.1021/ja037971+

Cited by 290 publications

(414 citation statements)

References 19 publications

(38 reference statements)

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“…This is close to the smallest nanowires synthesized experimentally 5 . The c-axis of the wire is in the (0001) direction of the wurtzite crystal structure.…”

Section: The Calculation Methodssupporting

confidence: 86%

“…This is a well established method which has produced electronic structures with excellent agreements with experiments for both CdSe nanowires 5 and quantum dots 12 . In the EPM method, the potential V(r) in the single electron Schrödinger's equation is described by the superposition of atomistic screened…”

Section: The Calculation Methodsmentioning

confidence: 76%

“…Nanowire can be synthesized by vapor-liquid-solid (VLS) method on a substrate 3 , or solution-liquid-solid (SLS) catalytic growth in a solvent 4,5 . It can also be synthesized by deposition along the surface steps 6 , and into the nanopores of aluminum oxide templates 7 .…”

Section: Introductionmentioning

confidence: 99%

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Single Particle Wavefunction Localizations in Bulged CdSe Nanowires

Zhao¹,

Wang²,

Wu³

2007

Jnl of Comp & Theo Nano

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Using atomistic empirical pseudopotentials, we have calculated the electronic structures of CdSe nanowires with a bulged area. The localized state wavefunctions and their binding energies are calculated, and their dependences on the bulged area shape are analyzed. We find that both the binding energy and the wavefunction localization strongly depend on the bulged area shape, with the most compact shape produces the largest binding energy and strongest wavefunction localization. We also find that the top of the valence band state has a weaker localization than the bottom of the conduction band state due to an effective mass anisotropy.

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“…This is close to the smallest nanowires synthesized experimentally 5 . The c-axis of the wire is in the (0001) direction of the wurtzite crystal structure.…”

Section: The Calculation Methodssupporting

confidence: 86%

Section: The Calculation Methodsmentioning

confidence: 76%

See 1 more Smart Citation

Single Particle Wavefunction Localizations in Bulged CdSe Nanowires

Zhao¹,

Wang²,

Wu³

2007

Jnl of Comp & Theo Nano

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“…Additionally the electronic properties of those nanostructures can be modified by size and dimensionality owing to quantum confinement effects as has been demonstrated for zero-and one-dimensional CdSe quantum structures by optical spectroscopy [2][3][4][5][6][7][8]. The onedimensionality of nanorods affords new properties like the polarized emission under photoexitation and electroluminescence [9,10].…”

mentioning

confidence: 98%

“…This mechanism was found for a few systems establishing III-V semiconductor rods and wires. Commonly used seeds are gold, bismuth, silver, or indium [4,7,14,15]. Usually such methods represent a two-step synthesis.…”

mentioning

confidence: 99%

Synthesis of InP Nanoneedles and Their Use as Schottky Devices

et al. 2009

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Indium phosphide (InP) nanostructures have been synthesized by means of colloidal chemistry. Under appropriate conditions needle-shaped nanostructures composed of an In head and an InP tail with lengths up to several micrometers could be generated in a one-pot synthesis. The growth is interpreted in terms of simultaneous decomposition of the In precursor and in situ generation of In and InP nanostructures. Owing to their specific design such In/InP nanoneedles suit the use as ready-made Schottky transistors. Their transfer and output characteristics are presented.Wet-chemically prepared semiconducting nanostructures are promising candidates for future electronic devices, not in the least due to their ability to accommodate whole device structures in a single nano-object [1]. Additionally the electronic properties of those nanostructures can be modified by size and dimensionality owing to quantum confinement effects as has been demonstrated for zero-and one-dimensional CdSe quantum structures by optical spectroscopy [2][3][4][5][6][7][8]. The onedimensionality of nanorods affords new properties like the polarized emission under photoexitation and electroluminescence [9,10]. A major drawback of the most frequently investigated materials is their chemical composition (chalocogenites of cadmium, lead, or mercury) and the toxicity resulting thereof. Presently, the most attractive and the less toxic alternative materials is InP, and, consequently, the corresponding nanowires are considered as building blocks for novel types of nanowirebased photo devices and solar cells [11]. On the other hand, the synthetic protocols for high quality InP nanostructures are still less developed than for II-VI and IV-VI materials, and also shape control is best established in II-VI systems (e.g. CdSe). Here the growth is controlled by the amount and type of added ligand molecules and allows the synthesis of rods, dots, or tetrapods [4,9,12]. The underlying growth mechanism is limited to semiconductors with an anisotropic crystal structure like wurzite since they expose facets with chemically distinguished reactivity; that is, the ligands preferentially bind to one family of surface planes resulting in a preferential growth in one direction. III-V semiconductors, however, possess a cubic zincblende lattice structure; that is, the required anisotropy of chemically different surfaces is not given. In this case another growth mechanism, the solutionliquid-solid (SLS) mechanism, can be exploited [13]. A liquid metal droplet acts as seed and catalyst for the crystal growth. This mechanism was found for a few systems establishing III-V semiconductor rods and wires. Commonly used seeds are gold, bismuth, silver, or indium [4,7,14,15]. Usually such methods represent a two-step synthesis. During the first step the metal seeds are produced by decomposing an organometallic pre- * Electronic address: weller@chemie.uni-hamburg.de cursor, whereas the dehalosylation reaction of InCl3 or InAc3 with tris-(trimethylsilyl)-phosphine (P(Si(CH)3)3, TMSP) in...

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Semiconductor Nanocrystal Quantum Dots

Hollingsworth

2005

Encyclopedia of Inorganic Chemistry

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Semiconductor quantum dots (QDs) bridge the gap between cluster molecules and bulk materials. The boundaries between molecular, QD, and bulk regimes are not well defined and are strongly material dependent. However, a range from ∼100 to ∼10 000 atoms per particle can be considered as a rough estimate of sizes for which the nanocrystal regime occurs. The lower limit of this range is determined by the stability of the bulk crystalline structure with respect to isomerization into molecular structures. The upper limit corresponds to sizes for which energy level spacings approach thermal energy, kT. In this nanosize regime, the semiconductor energy‐ or band gap is dependent upon the particle size. This phenomenon is known as the quantum‐size effect , and it allows band‐gap‐dependent material properties to be tuned with particle size. Specifically, semiconductor absorption and emission wavelengths can be controllably blueshifted from their bulk semiconductor values over hundreds of nanometers. Semiconductor quantum dots (QDs) have been prepared by a variety of ‘physical’ and ‘chemical’ methods. Here, we review the synthetic chemistry of QDs prepared by colloidal chemical routes. These QDs, known as nanocrystal quantum dots (NQDs), comprise an inorganic core overcoated with a layer of organic ligand molecules. The organic capping provides electronic and chemical passivation of surface dangling bonds, prevents uncontrolled growth and agglomeration of the nanoparticles, and allows NQDs to be chemically manipulated like large molecules with solubility and reactivity determined by the identity of the surface ligand. In contrast, with substrate‐bound epitaxial QDs prepared by physical deposition methods (e.g. molecular beam epitaxy and metal‐organic chemical vapor deposition), NQDs are ‘freestanding.’ In this discussion, we concentrate on the most successful synthesis methods, where success is determined by high crystallinity, adequate surface passivation, solubility in nonpolar or polar solvents, and good size monodispersity. Size monodispersity is critical as it permits the study and, ultimately, the use of materials‐size‐effects to define novel electronic, optical, and structural materials properties. Further, we examine many of the most significant contributions in the areas of NQD chemical surface modification (organic and inorganic), particle shape control, and phase control.

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Cadmium Selenide Quantum Wires and the Transition from 3D to 2D Confinement

Cited by 290 publications

References 19 publications

Single Particle Wavefunction Localizations in Bulged CdSe Nanowires

Single Particle Wavefunction Localizations in Bulged CdSe Nanowires

Synthesis of InP Nanoneedles and Their Use as Schottky Devices

Semiconductor Nanocrystal Quantum Dots

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