oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Growth and Characterization of Nickel Catalyzed Gallium Oxide Nanowires on Sapphire Substrate  [PDF]
Sudheer?Kumar,B. Srinivas?Goud,R.?Singh
Journal of Nano- and Electronic Physics , 2013,
Abstract: Beta gallium oxide ( -Ga2O3) nanowires (NWs) were synthesized via chemical vapor deposition in argon atmosphere using gallium as a precursor and sapphire substrate coated with ultra thin film of nickel (Ni). In this report, we report the growth of -Ga2O3 NWs as a function of deposition time. The structure and morphology of grown NWs were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The results revealed that single crystal growth of the NWs and their crystallinity improved with the increase in the deposition time. The diameter of -Ga2O3 NWs varied in the range between 40-80 nm and their length was observed up to many micrometers. The optical property of NWs was determined using UV-visible spectrophotometer and the bandgap of -Ga2O3 NWs was found to be about 4.30 eV.
Deposition of Aluminium Oxide Films by Pulsed Reactive Sputtering
Xinhui MAO,Bingchu CAI,Maosong WU,Guoping CHEN,
XinhuiMAO
,BingchuCAI,MaosongWU,GuopingCHEN

材料科学技术学报 , 2003,
Abstract: Pulsed reactive sputtering is a novel process used to deposit some compound films, which are not deposited by traditional D.C. reactive sputtering easily. In this paper some experimental results about the deposition of Al oxide films by pulsed reactive sputtering are presented. The hysteresis phenomenon of the sputtering voltage and deposition rate with the change of oxygen flow during sputtering process are discussed.
ZnO Nanowires Synthesized by Vapor Phase Transport Deposition on Transparent Oxide Substrates  [cached]
Yu Dongshan,Trad Tarek,McLeskey James,Craciun Valentin
Nanoscale Research Letters , 2010,
Abstract: Zinc oxide nanowires have been synthesized without using metal catalyst seed layers on fluorine-doped tin oxide (FTO) substrates by a modified vapor phase transport deposition process using a double-tube reactor. The unique reactor configuration creates a Zn-rich vapor environment that facilitates formation and growth of zinc oxide nanoparticles and wires (20–80 nm in diameter, up to 6 μm in length, density <40 nm apart) at substrate temperatures down to 300°C. Electron microscopy and other characterization techniques show nanowires with distinct morphologies when grown under different conditions. The effect of reaction parameters including reaction time, temperature, and carrier gas flow rate on the size, morphology, crystalline structure, and density of ZnO nanowires has been investigated. The nanowires grown by this method have a diameter, length, and density appropriate for use in fabricating hybrid polymer/metal oxide nanostructure solar cells. For example, it is preferable to have nanowires no more than 40 nm apart to minimize exciton recombination in polymer solar cells.
Gallium Arsenide Nanowires Formed by Au-assisted Metal-organic Chemical Vapor Deposition: Effect of Growth Temperature  [cached]
Rosnita Muhammad,Zulkafli Othaman,Yussof Wahab,Samsudi Sakrani
Modern Applied Science , 2009, DOI: 10.5539/mas.v3n7p73
Abstract: We have investigated the growth of gallium arsenide (GaAs) nanowires as a function of temperatures in metal organic chemical vapor deposition (MOCVD) to establish the mechanisms that govern wire growth and to optimize growth conditions. The growth follows the vapor-liquid-solid method by applying nanoparticle gold colloid as a catalyst to forms a eutectic liquid alloy with the substrate. The semi insulating undoped (111)B GaAs was first dipped in the poly-L-lysine solution before 30nm gold colloid dropped on the substrate surface. Growth process in the MOCVD system were done at temperatures between 380 and 600oC with growth time set is 30 min. All the grown samples were analyzed using a field emmission scanning electron microscope (FE-SEM) and scanning electron microscopy (SEM). With increasing temperature the nanowire height increases but leads to significant tapering of the nanowire due to competing growth at the (111) substrate surface. At low temperatures nanowires grown are cylindrical-shaped with diameter wires between 50 and 100 nm.
Growth control of GaAs nanowires using pulsed laser deposition with arsenic over pressure  [PDF]
X. W. Zhao,T. R. Lemberger,F. Y. Yang
Physics , 2007, DOI: 10.1088/0957-4484/18/48/485608
Abstract: Using pulsed laser ablation with arsenic over pressure, the growth conditions for GaAs nanowires have been systematically investigated and optimized. Arsenic over pressure with As$_2$ molecules was introduced to the system by thermal decomposition of polycrystalline GaAs to control the stoichiometry and shape of the nanowires during growth. GaAs nanowires exhibit a variety of geometries under varying arsenic over pressure, which can be understood by different growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs nanowires with uniform diameter, lengths over 20 $\mu$m, and thin surface oxide layer were obtained and can potentially be used for further electronic characterization.
Initial stages of nickel oxide growth on Ag(001) by pulsed laser deposition  [PDF]
S. H. Phark,Y. J. Chang,T. W. Noh,J. -S. Kim
Physics , 2009, DOI: 10.1103/PhysRevB.80.035426
Abstract: Submonolayers of nickel oxide films were grown on an Ag(001) by pulsed laser deposition, and characterized in-situ by both scanning tunneling microscopy and X-ray photoelectron spectroscopy. We observed quasi-two-dimensional growth of the film, and clearly identified several kinds of defects, such as embedded metallic Ni clusters and, notably, oxygen atoms, even while looking deeply into the substrate. These originated from Ni and O hyperthermal projectiles as well as from NiO clusters that were formed during laser ablation of a NiO target. Those defects played a role of nucleation sites in extending the nucleation stage of thin film growth.
Fabrication of various electrical resistances producing Zn nanowires and subsequent oxidation fabricating ZnO nanowires in PAA template by periodic and pulsed electrochemical deposition
Mahmood Moradi, Mina Zamanian and Mohammad Noormohammadi
Journal of Nanostructure in Chemistry , 2013, DOI: 10.1186/2193-8865-3-6
Abstract: Highly ordered anodic alumina template was produced by hard anodization. Barrier layer thickness was then reduced by a thinning process, and in the following Zn nanowires, it was grown in pores by periodic (AC) and pulsed electrochemical deposition. The samples were placed in a furnace for oxidation and for the possible preparation of electrical resistors. By measuring the electrical resistance of nanowire arrays, we did the calculations to find the electrical resistivity of each ZnO nanowire.
Template Assisted Growth of Zinc Oxide-Based Nanowires by Electrochemical Deposition  [PDF]
T. Singh,D.K. Pandya,R. Singh
Journal of Nano- and Electronic Physics , 2011,
Abstract: Ordered ZnO and Zn1 – xCdxO nanowire/nanorod arrays were fabricated by cathodic electrodeposition based on anodic alumina (AAO) membrane and polycarbonate membrane (PCM) from an aqueous solution containing zinc nitrate precursor at different bath temperatures. The electrodeposition process involves the electroreduction of nitrate ions to alter the local pH within the pores and precipitation of the metal oxide within the pores. X-Ray diffraction measurements showed that the nanowires/nanorods were of wurtzite crystallographic structures and the average length and diameter of nanorods were measured by SEM and TEM. HRTEM measurements confirm the crystallinity and elemental composition of grown nanowires on PCM/AAO templates.
Size-controlled growth of ZnO nanowires by catalyst-free high-pressure pulsed laser deposition and their optical properties
W. Z. Liu,H. Y. Xu,L. Wang,X. H. Li
AIP Advances , 2011, DOI: 10.1063/1.3605717
Abstract: Single crystalline ZnO nanowires were fabricated on Si (100) substrates by catalyst-free high-pressure pulsed laser deposition. It is found that the nanowires start to form when the substrate temperature and growth pressure exceed the critical values of 700 oC and 700 Pa, and their size strongly depends on these growth conditions. That is, the aspect ratio of the nanowires decreases with increasing temperature or decreasing pressure. Such a size dependence on growth conditions was discussed in terms of surface migration and scattering of ablated atoms. Room-temperature photoluminescence spectrum of ZnO nanowires shows a dominant near-band-edge emission peak at 3.28 eV and a visible emission band centered at 2.39 eV. Temperature-dependent photoluminescence studies reveal that the former consists of the acceptor-bound exciton and free exciton emissions; while the latter varies in intensity with the aspect ratio of the nanowires and is attributed to the surface-mediated deep level emission.
KrF pulsed laser deposition of chromium oxide thin films from Cr8O21 targets  [PDF]
N. Popovici,M. L. Parames,R. C. da Silva,O. Monnereau,P. M. Sousa,A. J. Silvestre,O. Conde
Physics , 2006, DOI: 10.1007/s00339-004-2795-7
Abstract: Chromium oxides, CrxOy, are of great interest due to the wide variety of their technological applications. Among them, CrO2 has been extensively investigated in recent years because it is an attractive compound to be used in spintronic heterostructures. However, its synthesis at low temperatures has been a difficult task due to the metastable nature of this oxide. This is indeed essential to ensure interface quality and the ability to coat thermal-sensitive materials such as those envisaged in spintronic devices. Pulsed Laser Deposition (PLD) is a technique that has the potential to meet the requirements stated above. In this work, we describe our efforts to grow chromium oxide thin films by PLD from Cr8O21 targets, using a KrF excimer laser. The as-deposited films were investigated by X-ray diffraction and Rutherford backscattering spectrometry. Structural and chemical composition studies showed that the films consist of a mixture of amorphous chromium oxides exhibiting different stoichiometries depending on the processing parameters, where nanocrystals of mainly Cr2O3 are dispersed. The analyses do not exclude the possibility of co-deposition of Cr2O3 and a low fraction of CrO2. PACS: 81.15.Fg, 75.50.Dd
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.