General Synthesis of Compound Semiconductor Nanowires.
About: This article is published in ChemInform.The article was published on 2000-05-16. It has received 115 citations till now. The article focuses on the topics: Nanowire.
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TL;DR: The synthesis of core–multishell structures, including a high-performance coaxially gated field-effect transistor, indicates the general potential of radial heterostructure growth for the development of nanowire-based devices.
Abstract: Semiconductor heterostructures with modulated composition and/or doping enable passivation of interfaces and the generation of devices with diverse functions. In this regard, the control of interfaces in nanoscale building blocks with high surface area will be increasingly important in the assembly of electronic and photonic devices. Core-shell heterostructures formed by the growth of crystalline overlayers on nanocrystals offer enhanced emission efficiency, important for various applications. Axial heterostructures have also been formed by a one-dimensional modulation of nanowire composition and doping. However, modulation of the radial composition and doping in nanowire structures has received much less attention than planar and nanocrystal systems. Here we synthesize silicon and germanium core-shell and multishell nanowire heterostructures using a chemical vapour deposition method applicable to a variety of nanoscale materials. Our investigations of the growth of boron-doped silicon shells on intrinsic silicon and silicon-silicon oxide core-shell nanowires indicate that homoepitaxy can be achieved at relatively low temperatures on clean silicon. We also demonstrate the possibility of heteroepitaxial growth of crystalline germanium-silicon and silicon-germanium core-shell structures, in which band-offsets drive hole injection into either germanium core or shell regions. Our synthesis of core-multishell structures, including a high-performance coaxially gated field-effect transistor, indicates the general potential of radial heterostructure growth for the development of nanowire-based devices.
2,022 citations
TL;DR: It is shown that precisely engineered buckling geometries can be created in nanoribbons of GaAs and Si in this manner and that these configurations can be described quantitatively with analytical models of the mechanics.
Abstract: Control over the composition, shape, spatial location and/or geometrical configuration of semiconductor nanostructures is important for nearly all applications of these materials. Here we report a mechanical strategy for creating certain classes of three-dimensional shapes in nanoribbons that would be difficult to generate in other ways. This approach involves the combined use of lithographically patterned surface chemistry to provide spatial control over adhesion sites, and elastic deformations of a supporting substrate to induce well-controlled local displacements. We show that precisely engineered buckling geometries can be created in nanoribbons of GaAs and Si in this manner and that these configurations can be described quantitatively with analytical models of the mechanics. As one application example, we show that some of these structures provide a route to electronics (and optoelectronics) with extremely high levels of stretchability (up to approximately 100%), compressibility (up to approximately 25%) and bendability (with curvature radius down to approximately 5 mm).
873 citations
TL;DR: In this article, the authors review recent advances in experimental methods for high spatial-resolution and high time-resolution thermometry and the application of these and related methods for measurements of thermal transport in low-dimensional structures.
Abstract: We review recent advances in experimental methods for high spatial-resolution and high time-resolution thermometry, and the application of these and related methods for measurements of thermal transport in low-dimensional structures. Scanning thermal microscopy (SThM) achieves lateral resolutions of 50 nm and a measurement bandwidth of 100 kHz: SThM has been used to characterize differences in energy dissipation in single-wall and multi-wall carbon nanotubes. Picosecond thermoreflectance enables ultrahigh time-resolution in thermal diffusion experiments and characterization of heat flow across interfaces between materials; the thermal conductance G of interfaces between dissimilar materials spans a relatively small range, 20
603 citations
TL;DR: The ability to produce efficient nanowire-based solar cells with a solution-based process and Earth-abundant elements could significantly reduce fabrication costs relative to existing high-temperature bulk material approaches.
Abstract: Nanowire-based solar cells offer open-circuit voltages and fill factors that are superior to those available from planar solar cells made of the same materials.
502 citations
TL;DR: This approach provides a route to the controlled fabrication of inorganic or hybrid silica nanostructures by living polymerization techniques by constructing the cylindrical polymer brushes themselves with a precursor-containing monomer.
Abstract: Precise control over the geometry of nanoscale one-dimensional structures is challenging. Cylindrical polymer brushes have now been used to synthesize organo-silica hybrid nanowires that are not only soluble in water but also in many organic solvents. There has been growing interest in the past decade in one-dimensional (1D) nanostructures, such as nanowires, nanotubes or nanorods, owing to their size-dependent optical and electronic properties and their potential application as building blocks, interconnects and functional components for assembling nanodevices1,2. Significant progress has been made; however, the strict control of the distinctive geometry at extremely small size for 1D structures remains a great challenge in this field. The anisotropic nature of cylindrical polymer brushes has been applied to template 1D nanostructured materials, such as metal, semiconductor or magnetic nanowires3,4,5,6. Here, by constructing the cylindrical polymer brushes themselves with a precursor-containing monomer, we successfully synthesized hybrid nanowires with a silsesquioxane core and a shell made up from oligo(ethylene glycol) methacrylate units, which are soluble in water and many organic solvents. The length and diameter of these rigid wires are tunable by the degrees of polymerization of both the backbone and the side chain. They show lyotropic liquid-crystalline behaviour and can be pyrolysed to silica nanowires. This approach provides a route to the controlled fabrication of inorganic or hybrid silica nanostructures by living polymerization techniques.
212 citations
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TL;DR: In this article, the authors describe the predictable synthesis of a broad range of binary and ternary III±V, II±VI, and IV±IV group semiconductor nanowires using the laser-assisted catalytic growth (LCG) method.
Abstract: The predictable synthesis of a broad range of multicomponent semiconductor nanowires has been accomplished using laser-assisted catalytic growth. Nanowires of binary group III±V materials (GaAs, GaP, InAs, and InP), ternary III±V materials (GaAs/P, InAs/P), binary II±VI compounds (ZnS, ZnSe, CdS, and CdSe), and binary SiGe alloys have been prepared in bulk quantities as high purity (>90 %) single crystals. The nanowires have diameters varying from three to tens of nanometers, and lengths extending to tens of micrometers. The synthesis of this wide range of technologically important semiconductor nanowires can be extended to many other materials and opens up significant opportunities in nanoscale science and technology. The synthesis of nanoscale materials is critical to work directed towards understanding fundamental properties of small structures, creating nanostructured materials, and developing nanotechnologies. Nanowires and nanotubes have been the focus of considerable attention because they have the potential to answer fundamental questions about one-dimensional systems and are expected to play a central role in applications ranging from molecular electronics to novel scanning microscopy probes. To explore such diverse and exciting opportunities requires nanowire materials for which the chemical composition and diameter can be varied. Over the past several years considerable effort has been placed on the bulk synthesis of nanowires, and while advances have been made using template, laser ablation, solution, and other methods, in no case has it been demonstrated that one approach could be exploited in a predictive manner to synthesize a wide range of nanowire materials. Here we describe the predictable synthesis of a broad range of binary and ternary III±V, II±VI, and IV±IV group semiconductor nanowires using the laser-assisted catalytic growth (LCG) method. Recently, we reported the growth of elemental Si and Ge nanowires using the LCG method, which exploits laser ablation to generate nanometer diameter catalytic clusters that define the size and direct the growth of the crystalline nanowires by a vapor±liquid±solid (VLS) mechanism. A key feature of the VLS growth process and our LCG method is that equilibrium phase diagrams can be used to predict catalysts and growth conditions, thereby enabling rational synthesis of new nanowire materials. Significantly, we show here that semiconductor nanowires of the III±V materials GaAs, GaP, GaAsP, InAs, InP, InAsP, the II±VI materials ZnS, ZnSe, CdS, CdSe, and IV±IV alloys of SiGe can be synthesized in high yield and purity using this approach. Compound semiconductors, such as GaAs and CdSe, are especially intriguing targets since their direct bandgaps give rise to attractive optical and electrooptical properties. The nanowires have been prepared as single crystals with diameters as small as 3 nm, which places them in a regime of strong radial quantum confinement, and lengths exceeding 10 mm. These studies demonstrate that LCG represents a very general and predictive approach for nanowire synthesis, and moreover, we believe that the broad range of III±V, II±VI, and IV±IV nanowires prepared will open up many new opportunities in nanoscale research and technology. The prediction of growth conditions for binary and more complex nanowires using the LCG method is, in principle, significantly more difficult than previous studies of elemental Si and Ge nanowires due to the complexity of ternary and higher order phase diagrams. However, this complexity can be greatly reduced by considering pseudobinary phase diagrams for the catalyst and compound semiconductor of interest. For example, the pseudobinary phase diagram of Au±GaAs shows that Au±Ga±As liquid and GaAs solid are the principle phases above 630 C in the GaAs rich region (Fig. 1). This implies that Au can serve as a catalyst to grow GaAs nanowires by the LCG method, if
1,429 citations