Nanowires chemical vapor deposition

Chemical vapor deposition, nanowires, 179 Cluster structures change in grain size, 5 ion-bombardment technique, 7-8 Cobalt molybdates, hydrodesulfurization catalysts, 2-3... 

Metal pair sites on supports, 63-64 Metalloorganic chemical vapor deposition, nanowires, 179 Metals... 

The approaches used for preparation of inorganic nanomaterials can be divided into two broad categories solution-phase colloidal synthesis and gas-phase synthesis. Metal and semiconductor nanoparticles are usually synthesized via solution-phase colloidal techniques,4,913 whereas high-temperature gas-phase processes like chemical vapor deposition (CVD), pulsed laser deposition (PLD), and vapor transfer are widely used for synthesis of high-quality semiconductor nanowires and carbon nanotubes.6,7 Such division reflects only the current research bias, as promising routes to metallic nanoparticles are also available based on vapor condensation14 and colloidal syntheses of high-quality semiconductor nanowires.15... 

Over the past few years, a large number of experimental approaches have been successfully used as routes to synthesize nanorods or nanowires based on titania, such as combining sol-gel processing with electrophoretic deposition,152 spin-on process,153 sol-gel template method,154-157 metalorganic chemical vapor deposition,158-159 anodic oxidative hydrolysis,160 sonochemical synthesis,161 inverse microemulsion method,162 molten salt-assisted and pyrolysis routes163 and hydrothermal synthesis.163-171 We will discuss more in detail the latter preparation, because the advantage of this technique is that nanorods can be obtained in relatively large amounts. 

The organometallic route can be extended to the formation of one-dimensional indium materials. On the use of long-chain amines as templates. In and InsSn nano wires have been prepared from the organometallic precursors InCp (Cp = 5115 ) in the presence of UV irradiation. In this case, irradiation is cmcial for the formation of the wires. In nanowires are also produced in the metal organic chemical vapor deposition grown InGaN layers. ... 

The OAG method has a general nature and can be applied to a variety of materials other than Si. Based on the OAG method, we have synthesized nanowires of a wide range of semiconducting materials including Ge [35], GaN [36, 37], GaAs [38, 39], GaP [41], SiG [40], and ZnO (whiskers) [42]. The actual OAG process was activated by laser ablation, hot-filament chemical vapor deposition (HFCVD) or thermal evaporation. 

Fundamental aspects of vapor-liquid-solid (VLS) semiconductor nanowire growth are presented here. The synthesis of VLS semiconductor has been extended to different reaction media and pathways from the early chemical vapor deposition (CVD) approach, including solution-liquid-solid (SLS) and supercritical fluid-liquid-solid (SFLS), laser-catalyzed growth, and vapor-liquid-solid-epitaxy. The properties of nanowires grown by these VLS embodiments are compared. In this entry, VLS growth of nanowire heterostructures and oriented and hyperbranched arrays is examined. In addition, surface passivation and functionalization are assessed, and the importance of these techniques in the progress toward VLS produced nanowire devices is detailed. 

Kamins, T.I. Williams, R.S. Basile, D.P. Harris, J.S. Ti-catalyzed Si nanowires by chemical vapor deposition microscopy and growth mechanisms. J. Appl. Phys. 2001, 89, 1008-1016. 

Wang, D. Dai, H. Low-temperature synthesis of single-crystal germanium nanowires by chemical vapor deposition. Angew. Chem., Int. Ed. 2002, 41 (24), 4783-4786. 

Mathur, S. Shen, H. Sivakov, V. Werner, U. Germanium nanowires and core-shell nanostructures by chemical vapor deposition of [Ge(C5H5)2j. Chem. Mater. 2004, 16 (12), 2449-2456. 

Hanrath, T. Korgel, B.A. Germanium nanowire transistors a comparison of electrical contacts patterned by electron beam lithography and beam-assisted chemical vapor deposition. J. Nanoeng. Nanosyst. 2005, 218, 25-34. 

Dozens of methods to synthesize nanotubes, nanowires, and nanorods have been reported that can be found in the references included in Table 1. In addition to the most well known ones, such as hot plasmas, laser ablation, chemical vapor deposition, high temperature solid state and hydrothermal synthesis, fill-ing/coating of carbon nanotubes and similar types of materials, three methods have been developed that enable the synthesis of a wealth of new anisotropic nanoparticles. 

Very recently Chen and coworkers [56] demonstrated the use of ElS for label-free electrochemical detection of DNA sequences relevant to anthrax lethal factor on gallium nitride (GaN) nanowires. The GaN nanowires were grown on a silicon substrate coated with Au catalyst using Ga as the source material and NH3 as the reactant gas in a tubular furnace via air pressure chemical vapor deposition. ElS measurements of the "as grown" GaN nanowires, observed in the Nyquist plot in Fig. 14.12A, exhibited a semicircle and a straight vertical line, indicative of finite impedance at the GaN/electrol3Ae... 

The evolution of modern vapor phase processes starts with metal catalyzed chemical vapor deposition and ends with laser vaporization (see Table I). Most vapor phase processes require metal particle catalysts some proceed without the addition of metal particles. The growth temperatures range from 100 to 4000°C. The length of silicon nanowires is <10 nm [74] that of carbon nanotubes is <300 jm [76] but they can be potentially endless [81]. 

Metal particle catalyzed chemical vapor deposition is the most versatile VLS process (Table II) yielding a wide range of single crystal whiskers and nanowhiskers [1-2] [5-6], short amorphous or polycrystalline fibers [1] [7], and nanotubes [8]. Laser ablation of selected metal alloys is a recent VLS process used for the synthesis of semiconductor nanowire [74]. Metal particle catalyzed carbothermal reduction, another VLS process, yields single crystal whiskers [9-10]. Metal catalyzed arc discharge [11], metal particle catalyzed laser ablation [12], and metal particle catalyzed plasma arc discharge [13] yield nanotubes by a VLS mechanism. 

A nanowire is a nanostructure, with the diameter of the order of a nanometer and aspect ratio greater than 10 1. Chemical vapor deposition. 

The pyrolysis or chemical vapor deposition of a metal precursor, a volatile complex such as FeCp2, CoCp2, or NiCp2, and a carbon source, such as acetylene, toluene, dichlorobenzene, or Cgo, also permits the simultaneous synthesis of CNTs and confined metal nanowires. Encapsulated nanowires of Fe [56,178-181], FeCo [69], and FeNi [182] within CNTs were synthesized using elevated temperatures. When [Co(CO)3NO] was used both as catalyst and the source for CNT growth, the nanowires and the filling yields were poor [183]. 

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