Changshi Lao

Density-controlled growth of aligned ZnO nanowire arrays by seedless chemical approach on smooth surfaces

A novel ZnO seedless chemical approach for density-controlled growth of ZnO nanowire (NW) arrays has been developed. The density of ZnO NWs is controlled by changing the precursor concentration. Effects of both growth temperature and growth time are also investigated. By this novel synthesis technique, ZnO NW arrays can grow on any substrate (polymer, glass, semiconductor, metal, and more) as long as the surface is smooth. This technique represents a new, low-cost, time-efficient, and scalable method for fabricating ZnO NW arrays for applications in field emission, vertical field effect transistor arrays, nanogenerators, and nanopiezotronics.

Morphological tuning and conductivity of organic conductor nanowires

We report the synthesis of small-molecule organic conductor nanowires of TTF-TCNQ by selective inducement in a two-phase method by pi-pi stacking interaction. The morphologies of TTF-TCNQ, from straight nanowires to helical nanowires and to complicated helical dendrite structures, have been controlled by adjusting the experimental conditions. The technique has been applied to the synthesis of AgTCNQ/CuTCNQ nanowires in a two-phase system of acetonitrile/hexane. I-V characterization of an individual nanowire indicated that the conductivity along the b-axis of the TTF-TCNQ helical nanowire is much better than that along other directions. The synthetic procedure presented is a general approach for producing controlled organic conductor/semiconductor nanowires.

Quantifying oxygen diffusion in ZnO nanobelt

A method is presented for quantifying oxygen diffusion behavior in a nanodevice fabricated using individual ZnO nanowire/nanobelt. A nanodevice was built using a single nanobelt. Defects are introduced into nanobelt during specific nanofabrication procedure. Then, after the device being exposed to atmosphere for several days, oxygen in air diffused into the nanobelt and significantly changed the conductivity of the device. By comprising the experimentally measured conductivity and that of simulated result, the diffusion coefficient of oxygen in ZnO nanowires/nanobelts has been derived.

ZnO nanostructures for optoelectronic applications

In this Paper we present growth and characterization of ZnO nanowires on wideband gap substrates, such as SiC and GaN. Experimental results on the ZnO nanowires grown on p-SiC and p-GaN are presented with growth morphology, structure analysis, and dimensionality control. We also present experimental results on individual nanowires such as I-V measurements and UV sensitivity measurements with use of polymer coating on ZnO nanowires. The ZnO nanowires can be used for a variety of nanoscale optical and electronics applications.

Growth and characterization of ZnO nanowires for various sensor applications

In this Paper we present growth and characterization of ZnO nanowires on a variety of substrates, such as Silicon and SiC. Experimental results on the ZnO nanowires grown on Si and SiC are presented with growth morphology, structure analysis, and dimensionality control. The ZnO nanowires can be used for a variety of nanoscale optical and electronics sensors.

Packaging of ZnO nanobelts as nanosensors: Synthesis, Alignment and Characterization

One-dimensional ZnO nanobelt exhibits unique properties which makes it a perfect candidate for sensors in various applications. In this paper, synthesis of ZnO nanobelts is described. Design and fabrication of electrodes are presented. Alignment of nanobelts, which is assisted by the optimized designed electrode, is discussed. Dramatic improvement of the contact resistance is found after the sample is annealed at 500degC for 1 min. This work lays the foundation for further fabrication, fictionalization and packaging of ZnO nanobelt based sensors

A review of growth and characterization of ZnO nanostructures for various optical applications

The ZnO nanostructures can be implemented in optoelectronic applications, piezoelectric pressure sensors, Spintronic devices, transducers and biomedical applications [1-8]. Use of these nanostructures, will also allow building of nanoscale nanosensors, nanocantilevers, field-effect transistors and nanoresonators for a variety of military, homeland security and, commercial applications. In this paper we review growth and characterization of ZnO nanowires on a variety of substrates. Experimental results on the ZnO nanowires grown on GaN and SiC are presented with growth morphology, structure analysis, and dimensionality control. We also discuss Raman and micro-Raman spectroscopy for characterization of ZnO nanostructures.

Vertically-Aligned ZnO Nanowire Arrays and Their Application as UV Sensors

As a direct wide band-gap (3.37eV) semiconductor with a large exciton binding energy (60meV), ZnO is one of the most important semiconductor materials for applications in optoelectronics, sensors, and actuators. For the known one-dimensional (1D) nanomaterials, ZnO nanowires and nanobelts are among the most promising and most extensively studied 1D nanostructures due to their interesting properties. Recently, growth of vertical aligned nanowire arrays have received considerable attention not only for fabricating array of vertical field effect transistors, but more importantly due to their applications in nanogenerators and nanopiezotronics for converting mechanical energy into electrical energy and fabricating piezoelectric-semiconducting coupled devices.