Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cadmium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section with typical widths of 30 to 300 nanometers, width-to-thickness ratios of 5 to 10, and lengths of up to a few millimeters. The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. The nanobelts could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and building functional devices along individual nanobelts.

https://science.sciencemag.org/content/sci/291/5510/1947.full.pdf

Nanobelts of Semiconducting Oxides

Bulk quantities of defect-free silicon (Si) nanowires with nearly uniform diameters ranging from 40 to 50 angstroms were grown to a length of several micrometers with a supercritical fluid solution-phase approach. Alkanethiol-coated gold nanocrystals (25 angstroms in diameter) were used as uniform seeds to direct one-dimensional Si crystallization in a solvent heated and pressurized above its critical point. The orientation of the Si nanowires produced with this method could be controlled with reaction pressure. Visible photoluminescence due to quantum confinement effects was observed, as were discrete optical transitions in the ultraviolet-visible absorbance spectra.

http://science.sciencemag.org/content/sci/287/5457/1471.full.pdf

Control of Thickness and Orientation of Solution-Grown Silicon Nanowires

The ever increasing requirements for electrical performance of on-chip wiring has driven three major technological advances in recent years. First, copper has replaced Aluminum as the new interconnect metal of choice, forcing also the introduction of damascene processing. Second, alternatives for SiO2 with a lower dielectric constant are being developed and introduced in main stream processing. The many new resulting materials needs to be classified in terms of their materials characteristics, evaluated in terms of their properties, and tested for process compatibility. Third, in an attempt to lower the dielectric constant even more, porosity is being introduced into these new materials. The study of processes such as plasma interactions and swelling in liquid media now becomes critical. Furthermore, pore sealing and the deposition of a thin continuous copper diffusion barrier on a porous dielectric are of prime importance. This review is an attempt to give an overview of the classification, the character...

Low dielectric constant materials for microelectronics

There are growing concerns over the environmental, climate, and health impacts caused by using non-renewable fossil fuels. The utilization of green energy, including solar and wind power, is believed to be one of the most promising alternatives to support more sustainable economic growth. In this regard, lithium-ion batteries (LIBs) can play a critically important role. To further increase the energy and power densities of LIBs, silicon anodes have been intensively explored due to their high capacity, low operation potential, environmental friendliness, and high abundance. The main challenges for the practical implementation of silicon anodes, however, are the huge volume variation during lithiation and delithiation processes and the unstable solid-electrolyte interphase (SEI) films. Recently, significant breakthroughs have been achieved utilizing advanced nanotechnologies in terms of increasing cycle life and enhancing charging rate performance due partially to the excellent mechanical properties of nanomaterials, high surface area, and fast lithium and electron transportation. Here, the most recent advance in the applications of 0D (nanoparticles), 1D (nanowires and nanotubes), and 2D (thin film) silicon nanomaterials in LIBs are summarized. The synthetic routes and electrochemical performance of these Si nanomaterials, and the underlying reaction mechanisms are systematically described.

Silicon-based Nanomaterials for Lithium-Ion Batteries - A Review

Monodisperse silicon nanowires were synthesized by exploiting well-defined gold nanoclusters as catalysts for one-dimensional growth via a vapor–liquid–solid mechanism. Transmission electron microscopy studies of the materials grown from 5, 10, 20, and 30 nm nanocluster catalysts showed that the nanowires had mean diameters of 6, 12, 20, and 31 nm, respectively, and were thus well defined by the nanocluster sizes. High-resolution transmission electron microscopy demonstrated that the nanowires have single-crystal silicon cores sheathed with 1–3 nm of amorphous oxide and that the cores remain highly crystalline for diameters as small as 2 nm.

/pdf/diameter-controlled-synthesis-of-single-crystal-silicon-3liaiih7v0.pdf

Diameter-controlled synthesis of single-crystal silicon nanowires

A hybrid preparative method was developed to prepare organosulfur-functionalized Au nanoparticles (NPs) on silicon nanowires (SiNWs) by reacting HAuCl4 with SiNW in the presence of thiol. A number of organosulfur moleculesdodecanethiol, hexanethiol, 1,6-hexanedithiol, and tioproninwere used to functionalize the Au surface. Size-selected NPs ranging from 1.6 to 7.5 nm were obtained by varying the S/Au ratio and the concentration of HAuCl4. This method was further extended to the preparation Pd and Pd−Au bimetallic NPs on SiNWs. The morphology of the metal nanostructures was examined by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The local structure and bonding of the SiNW-supported metal nanostructures were studied using X-ray absorption fine structures (XAFS) [including both X-ray near-edge structures (XANES) and extended X-ray absorption fine structures (EXAFS)] at the Au L3-, Pd K-, S K-, and Si K-edges. It was also found that the annealing of the...

Organosulfur-functionalized Au, Pd, and Au-Pd nanoparticles on 1D silicon nanowire substrates: preparation and XAFS studies.

Deposition of carbon nanotubes on Si nanowires by chemical vapor deposition

A soft X-ray absorption study of nanodiamond films prepared by hot-filament chemical vapor deposition

By ablating a silicon monoxide target with a pulsed KrF excimer laser at 1200 °C in an Ar atmosphere, we have achieved production of high-purity Si nanowires in bulk quantities. The yield and linear growth rate can reach 30 mg/h and 500 μm/h, respectively. Transmission electron micrographs show that the sample of silicon nanowires consists of few nanoparticles.

Y. H. Tang

Papers

Organosulfur-functionalized Au, Pd, and Au-Pd nanoparticles on 1D silicon nanowire substrates: preparation and XAFS studies.

Deposition of carbon nanotubes on Si nanowires by chemical vapor deposition

A soft X-ray absorption study of nanodiamond films prepared by hot-filament chemical vapor deposition

Si nanowires synthesized from silicon monoxide by laser ablation

Carbon monoxide-assisted growth of carbon nanotubes