The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

Room-temperature ultraviolet lasing in semiconductor nanowire arrays has been demonstrated The self-organized, oriented zinc oxide nanowires grown on sapphire substrates were synthesized with a simple vapor transport and condensation process These wide band-gap semiconductor nanowires form natural laser cavities with diameters varying from 20 to 150 nanometers and lengths up to 10 micrometers Under optical excitation, surface-emitting lasing action was observed at 385 nanometers, with an emission linewidth less than 03 nanometer The chemical flexibility and the one-dimensionality of the nanowires make them ideal miniaturized laser light sources These short-wavelength nanolasers could have myriad applications, including optical computing, information storage, and microanalysis

Room-temperature ultraviolet nanowire nanolasers

We have converted nanoscale mechanical energy into electrical energy by means of piezoelectric zinc oxide nanowire (NW) arrays. The aligned NWs are deflected with a conductive atomic force microscope tip in contact mode. The coupling of piezoelectric and semiconducting properties in zinc oxide creates a strain field and charge separation across the NW as a result of its bending. The rectifying characteristic of the Schottky barrier formed between the metal tip and the NW leads to electrical current generation. The efficiency of the NW-based piezoelectric power generator is estimated to be 17 to 30%. This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.

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Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays

A family of highly ordered mesoporous (20−300 A) silica structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media. Periodic arrangements of mescoscopically ordered pores with cubic Im3m, cubic Pm3m (or others), 3-d hexagonal (P63/mmc), 2-d hexagonal (p6mm), and lamellar (Lα) symmetries have been prepared. Under acidic conditions at room temperature, the nonionic oligomeric surfactants frequently form cubic or 3-d hexagonal mesoporous silica structures, while the nonionic triblock copolymers tend to form hexagonal (p6mm) mesoporous silica structures. A cubic mesoporous silica structure (SBA-11) with Pm3m diffraction symmetry has been synthesized in the presence of C16H33(OCH2CH2)10OH (C16EO10) surfactant species, while a 3-d hexagonal (P63/mmc) mesoporous silica structure (SBA-12) results when C18EO10 is used. Surfactants with short EO segments tend to form lamellar mesost...

Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures

There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

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High-performance lithium battery anodes using silicon nanowires

We have synthesized a variety of novel gold and palladium nanostructures by using simple aqueous solution growth approaches. In this conference, I will describe our recent work on the seed-mediated synthesis of palladium nanorods and branched nanocrystals. Hydrothermal synthesis of monodispersed octahedral gold nanocrystals and their self-assembled structures will be presented. The optical, SERS, and catalytic properties of these nanostructures will also be discussed.

Aqueous solution syntheses of palladium nanorods and gold octahedra and their assembly

PROBLEM TO BE SOLVED: To obtain one-dimensional nanostructures having a diameter along the longitudinal axis which does not vary more than approximately 10% in the section exhibiting the maximum change in the diameter, and having a diameter of less than approximately 200 nm at the point of the maximum diameter. SOLUTION: One-dimensional nanostructures have uniform diameters of less than approximately 200 nm. These new nanostructures, which are referred to as "nanowires", include single-crystal homostructures as well as heterostructures of at least two single-crystal materials having different chemical compositions. Because single-crystal materials are used to form the heterostructure, the resultant heterostructure will be single-crystal as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN). COPYRIGHT: (C)2010,JPO&INPIT

Method of fabricating nanostructure and nanowire and device fabricated therefrom

Expression of concern for 'Surface-dependent band structure variations and bond deviations of GaN' by Chih-Shan Tan et al., Phys. Chem. Chem. Phys., 2022, 24, 9135-9140, https://doi.org/10.1039/D2CP00100D.

Expression of concern: Surface-dependent band structure variations and bond deviations of GaN.

Complete regioselectivity for formation of 1,4-triazoles is obtained using gold rhombic dodecahedra.

Michael H. Huang

Papers

Aqueous solution syntheses of palladium nanorods and gold octahedra and their assembly

Method of fabricating nanostructure and nanowire and device fabricated therefrom

Expression of concern: Surface-dependent band structure variations and bond deviations of GaN.

Control of Regioselectivity over Gold Nanocrystals of Different Surfaces for the Synthesis of 1,4-Disubstituted Triazole Through the Click Reaction.