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. ...

/pdf/a-comprehensive-review-of-zno-materials-and-devices-21a3zjadem.pdf

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.

/pdf/piezoelectric-nanogenerators-based-on-zinc-oxide-nanowire-1swcm3u2x8.pdf

Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays

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.

/pdf/high-performance-lithium-battery-anodes-using-silicon-58e1j6kr4f.pdf

High-performance lithium battery anodes using silicon nanowires

Zinc oxide is a unique material that exhibits semiconducting and piezoelectric dual properties. Using a solid–vapour phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobelts, nanowires and nanocages of ZnO have been synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by the solid–vapour phase technique and their corresponding growth mechanisms. The application of ZnO nanobelts as nanosensors, nanocantilevers, field effect transistors and nanoresonators is demonstrated.

/pdf/zinc-oxide-nanostructures-growth-properties-and-applications-8d5hcz3lg8.pdf

Zinc oxide nanostructures: growth, properties and applications

Catalytic Growth of Zinc Oxide Nanowires by Vapor Transport.

PROBLEM TO BE SOLVED: To provide a method of fabricating nanostructures and nanowires and a device fabricated therefrom. SOLUTION: A one-dimensional nanostructure has a uniform diameter of less than approximately 200 nm. Such new nanostructure which is called as "a nanowire" includes a single-crystal homostructure as well as heterostructure of at least two single crystal materials having different chemical compositions. Because the single crystal material is used to form the heterostructure, the resultant heterostructure may be a single crystal as well. The nanowire heterostructure is generally based on a semiconducting wire in which 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 nanostructures and nanowires and device fabricated therefrom

Photoluminescence (PL) and Time-resolved PL (TR-PL) are used to measure the luminescence energy and carrier lifetime of InGaN/GaN quantum well (QW) structures as a function of biaxial strain and excitation density. A blueshift of the transition energy and a decrease in the carrier lifetime reveal a field-dependent spatial electron-hole (e-h) wavefunction separation. This behavior is observed both under the application of tensile, biaxial strain, which directly affects the piezo-related field, and under increased excitation density, which effectively screens the electric field. Our results show an increased carrier separation with increasing QW thickness.

Luminescence energy and carrier lifetime as a function of applied biaxial strain in InGaN/GaN quantum-well structures

Verfahren zur herstellung nanostrukturen und nanodrähten und durch diese verfahren hergestellte anordnungen

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

Henning Feick

Papers

Catalytic Growth of Zinc Oxide Nanowires by Vapor Transport.

Method of fabricating nanostructures and nanowires and device fabricated therefrom

Luminescence energy and carrier lifetime as a function of applied biaxial strain in InGaN/GaN quantum-well structures

Verfahren zur herstellung nanostrukturen und nanodrähten und durch diese verfahren hergestellte anordnungen

Method of fabricating nanostructure and nanowire and device fabricated therefrom