Preparation of ZnO nanowires by electrochemical deposition

AbstractThis work reports the results from the synthesis of nanostructured ZnO thin films via electrochemical deposition on glass substrates coated with F doped SnO2. The influence of the deposition parameters on the properties of the obtained ZnO films was studied. The Raman spectra of the ZnO films contain the typical for ZnO vibrational bands. The scanning electron microscope micrographs demonstrate that the films consist of ZnO nanowires. Growing of ZnO in the conditions with addition of H2O2 in lower concentration and without flowing air results in larger grain formation. The ZnO layers demonstrate high diffuse reflection

SiC Nanorods Grown on Electrospun Nanofibers Using Tb as Catalyst: Fabrication, Characterization, and Photoluminescence Properties

Well-crystallizedβ-SiC nanorods grown on electrospun nanofibers were synthesized by carbothermal reduction of Tb doped SiO2(SiO2:Tb) nanofibers at 1,250 °C. The as-synthesized SiC nanorods were 100–300 nm in diameter and 2–3 μm in length. Scanning electron microscopy (SEM) results suggested that the growth of the SiC nanorods should be governed by vapor-liquid-solid (VLS) mechanism with Tb metal as catalyst. Tb(NO3)3particles on the surface of the electrospun nanofibers were decomposed at 500 °C and later reduced to the formation of Tb nanoclusters at 1,200 °C, and finally the formation of a Si–C–Tb ally droplet will stimulate the VLS growth at 1,250 °C. Microstructure of the nanorod was further investigated by transmission electron microscopy (TEM). It was found that SiC <111> is the preferred initial growth direction. The liquid droplet was identified to be Si86Tb14, which acted as effective catalyst. Strong green emissions were observed from the SiC nanorod samples. Four characteristic photoluminescence (PL) peaks of Tb ions were also identified

Laser modification of silver and gold nanoparticles in dielectric thin films

International audienceThin films of SiO2 containing silver or gold nanoparticles were prepared by magnetron co-sputtering followed by thermal annealing. The concentration of metal in the films was determined by Rutherford backscattering. Laser treatment of the films was performed using the second or fourth harmonic of a Nd: YAG laser with a pulse length of 5 ns and frequency of 10 Hz. Laser fluences were below 125 mJ/cm2. The changes induced in the films by the laser radiation were monitored by measuring the optical absorption. A marked difference in the effect of laser radiation on the nanoparticles in the case of Ag and Au was found. For silver, a laser induced fragmentation of the nanoparticles was observed and in the range of laser energies studied the final mean particle size scaled linearly with laser fluence without a major reduction of the amount of precipitated metal. In the case of gold, such a dependence on laser fluence could not be shown and in some cases the intensity of the surface plasmon resonance was greatly reduced. The mechanism of interaction of the laser light with the metal nanoparticles is discussed

Instability phenomena in µc-Si:H solar cells prepared by hot-wire CVD

We have investigated the various types of instability phenomena in mu c-Si:H solar cells prepared by HWCVD under conditions close to the transition to amorphous growth, resulting in compact material, and other cells containing a high crystalline volume fraction of material with a pronounced porosity.It was found that light-induced degradation is most pronounced for material with some amorphous volume fraction while highly crystalline material is stable under illumination. On the other hand, we have observed a strong degradation of the current-voltage (J-V) parameters after treatment in de-ionized water of the cells with highly crystalline i-layers, while cells with compact i-layer material show very little changes. (c) 2005 Elsevier B.V. All rights reserved

Experimental Study Of Interaction Of Laser Radiation With Silver Nanoparticles In Sio2 Matrix

Thin films of silica containing silver nanoparticles were deposited by magnetron co-sputtering followed by thermal annealing in air or Ar+2% H 2. Laser fragmentation of the particles was carried out at two different wavelengths. The films were characterized by UV-VIS absorption spectroscopy and plasmon resonance numerical modeling based on the Mie theory, together with Rutherford backscattering elemental analysis, X-ray photoelectron spectroscopy chemical characterization, combined with statistical analysis of the transmission electron microscopy micrographs, and surface topography study by atomic force microscopy. It is demonstrated that the fragmentation is a result of a thermal process and its mechanism does not depend on the laser wavelength as long as the laser light is absorbed by the silver particles. Laser treatment with moderate fluences does not alter the precipitated metal content while fragmenting the particles. TEM study indicates that laser assisted silver particle modification can serve as a method for narrowing the particle size distribution. Copyright © 2006 American Scientific Publishers All rights reserved