Home About us Contact
|
Home About us Contact | ||
|
|
||
Nanowire Growth (nanowire + growth)
Selected AbstractsElectrically Controlled Catalytic Nanowire Growth from SolutionADVANCED MATERIALS, Issue 34 2009August Dorn Electric-field-induced catalytic growth of cadmium selenide nanowires from solution is demonstrated. Our approach highlights the importance of electric field and surface-charge density for catalytic nanowire growth. In addition, this method is compatible with conventional silicon-based technology, and we demonstrate in situ device fabrication at temperatures below 300 °C. [source] Cover Picture: Dendritic Nanowire Growth Mediated by a Self-Assembled Catalyst (Adv. Mater.ADVANCED MATERIALS, Issue 5 20055/2005) Abstract The dendritic nanostructures shown on the cover background were generated by self-assembled Mn clusters deposited from the vapor phase during vapor,liquid,solid growth of InAs nanowires. By carefully controlling the timing and amount of the Mn precursor, on p.,598 Lauhon and co-workers demonstrate a route to the formation of ordered hierarchical nanowire structures shown from various perspectives in the cover insets. [source] Directionally Integrated VLS Nanowire Growth in a Local Temperature Gradient,ANGEWANDTE CHEMIE, Issue 40 2009Geunhee Lee Dr. Ganz gerade: Ein einfacher und robuster Mechanismus richtet die Wachstumsrichtungen von Nanodrähten mithilfe eines lokalen Temperaturgradienten als lokaler kinetischer Variable während eines üblichen Dampf-flüssig-fest(VLS)-Wachstums kohärent aus (siehe Bild, Maßstab=200,,m). Die Nanodrähte wachsen gerade in die senkrechte Richtung, zeigen in der Nähe der katalytischen Spitzen aber Knicke. [source] Controlled Nucleation of GaN Nanowires Grown with Molecular Beam EpitaxyADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Kris A. Bertness Abstract The location of GaN nanowires is controlled with essentially perfect selectivity using patterned SiNx prior to molecular beam epitaxy growth. Nanowire growth is uniform within mask openings and absent on the mask surface for over 95% of the usable area of a 76 mm diameter substrate. The diameters of the resulting nanowires are controlled by the size of the mask openings. Openings of approximately 500 nm or less produce single nanowires with symmetrically faceted tips. [source] Preferential Interface Nucleation: An Expansion of the VLS Growth Mechanism for NanowiresADVANCED MATERIALS, Issue 2 2009Brent A. Wacaser Abstract A review and expansion of the fundamental processes of the vapor,liquid,solid (VLS) growth mechanism for nanowires is presented. Although the focus is on nanowires, most of the concepts may be applicable to whiskers, nanotubes, and other unidirectional growth. Important concepts in the VLS mechanism such as preferred deposition, supersaturation, and nucleation are examined. Nanowire growth is feasible using a wide range of apparatuses, material systems, and growth conditions. For nanowire growth the unidirectional growth rate must be much higher than growth rates of other surfaces and interfaces. It is concluded that a general, system independent mechanism should describe why nanowires grow faster than the surrounding surfaces. This mechanism is based on preferential nucleation at the interface between a mediating material called the collector and a crystalline solid. The growth conditions used mean the probability of nucleation is low on most of the surfaces and interfaces. Nucleation at the collector-crystal interface is however different and of special significance is the edge of the collector-crystal interface where all three phases meet. Differences in nucleation due to different crystallographic interfaces can occur even in two phase systems. We briefly describe how these differences in nucleation may account for nanowire growth without a collector. Identifying the mechanism of nanowire growth by naming the three phases involved began with the naming of the VLS mechanism. Unfortunately this trend does not emphasize the important concepts of the mechanism and is only relevant to one three phase system. We therefore suggest the generally applicable term preferential interface nucleation as a replacement for these different names focusing on a unifying mechanism in nanowire growth. [source] Controlled Synthesis of CdSe Nanowires by Solution,Liquid,Solid MethodADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Zhen Li Abstract Semiconductor nanowires prepared by wet chemical methods are a relatively new field of 1D electronic systems, where the dimensions can be controlled by changing the reaction parameters using solution chemistry. Here, the solution,liquid,solid approach where the nanowire growth is governed by low-melting-point catalyst particles, such as Bi nanocrystals, is presented. In particular, the focus is on the preparation and characterization of CdSe nanowires, a material which serves a prototype structure for many kinds of low dimensional semiconductor systems. To investigate the influence of different reaction parameters on the structural and optical properties of the nanowires, a comprehensive synthetic study is presented, and the results are compared with those reported in literature. How the interplay between different reaction parameters affects the diameter, length, crystal structure, and the optical properties of the resultant nanowires are demonstrated. The structural properties are mainly determined by competing reaction pathways, such as the growth of Bi nanocatalysts, the formation and catalytic growth of nanowires, and the formation and uncatalytic growth of quantum dots. Systematic variation of the reaction parameters (e.g., molecular precursors, concentration and concentration ratios, organic ligands, or reaction time, and temperature) enables control of the nanowire diameter from 6 to 33,nm, while their length can be adjusted between several tens of nanometers and tens of micrometers. The obtained CdSe nanowires exhibit an admixture of wurtzite (W) and zinc blende (ZB) structure, which is investigated by X-ray diffraction. The diameter-dependent band gaps of these nanowires can be varied between 650 and 700,nm while their fluorescence intensities are mainly governed by the Cd/Se precursor ratio and the ligands used. [source] Electrically Controlled Catalytic Nanowire Growth from SolutionADVANCED MATERIALS, Issue 34 2009August Dorn Electric-field-induced catalytic growth of cadmium selenide nanowires from solution is demonstrated. Our approach highlights the importance of electric field and surface-charge density for catalytic nanowire growth. In addition, this method is compatible with conventional silicon-based technology, and we demonstrate in situ device fabrication at temperatures below 300 °C. [source] Preferential Interface Nucleation: An Expansion of the VLS Growth Mechanism for NanowiresADVANCED MATERIALS, Issue 2 2009Brent A. Wacaser Abstract A review and expansion of the fundamental processes of the vapor,liquid,solid (VLS) growth mechanism for nanowires is presented. Although the focus is on nanowires, most of the concepts may be applicable to whiskers, nanotubes, and other unidirectional growth. Important concepts in the VLS mechanism such as preferred deposition, supersaturation, and nucleation are examined. Nanowire growth is feasible using a wide range of apparatuses, material systems, and growth conditions. For nanowire growth the unidirectional growth rate must be much higher than growth rates of other surfaces and interfaces. It is concluded that a general, system independent mechanism should describe why nanowires grow faster than the surrounding surfaces. This mechanism is based on preferential nucleation at the interface between a mediating material called the collector and a crystalline solid. The growth conditions used mean the probability of nucleation is low on most of the surfaces and interfaces. Nucleation at the collector-crystal interface is however different and of special significance is the edge of the collector-crystal interface where all three phases meet. Differences in nucleation due to different crystallographic interfaces can occur even in two phase systems. We briefly describe how these differences in nucleation may account for nanowire growth without a collector. Identifying the mechanism of nanowire growth by naming the three phases involved began with the naming of the VLS mechanism. Unfortunately this trend does not emphasize the important concepts of the mechanism and is only relevant to one three phase system. We therefore suggest the generally applicable term preferential interface nucleation as a replacement for these different names focusing on a unifying mechanism in nanowire growth. [source] Vapor,Solid,Solid Growth Mechanism Driven by Epitaxial Match between Solid AuZn Alloy Catalyst Particles and ZnO Nanowires at Low Temperatures,ADVANCED MATERIALS, Issue 8 2008Leonardo C. Campos A comprehensive explanation for the precise mechanism of ZnO nanowire growth at low temperatures (T,<,400,°C) is presented. Experimental data and theoretical considerations evidence that ZnO nanowires originate from solid ,-AuZn catalyst particles. A model is proposed to describe such growth. An original feature of the model concerns the formation of nanowire, which occurs via preferential oxidation of specific ,-AuZn surfaces induced by epitaxial-like growth mechanism. [source] Nucleation and Growth of Boron Nanowires on ZrB2 Particles,CHEMICAL VAPOR DEPOSITION, Issue 7 2006L. Guo Abstract Amorphous boron rich nanowires are grown on ZrB2 particles using diborane as the gas precursor in a CVD process under 20,Torr pressure and at 900,°C. These nanowires have uniform diameters of tens of nanometers and lengths of up to several micrometers. The boron-rich nanowires are characterized and found to be composed of boron clusters containing unit cells of icosahedral B12. A surface nucleation and growth mechanism of solid boron from vapor phase is proposed to explain the nanowire growth. The role of ZrB2 particles in the synthesis of the boron-rich nanostructures is also discussed. [source] Aqueous-Solution Growth of GaP and InP Nanowires: A General Route to Phosphide, Oxide, Sulfide, and Tungstate NanowiresCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2004Yujie Xiong Dr. Abstract A general synthetic route has been developed for the growth of metal phosphide, oxide, sulfide, and tungstate nanowires in aqueous solution. In detail, cetyltrimethylammonium cations (CTA+) can be combined with anionic inorganic species along a co-condensation mechanism to form lamellar inorganic,surfactant intercalated mesostructures, which serve as both microreactors and reactants for the growth of nanowires. For example, GaP, InP, ,-MnO2, ZnO, SnS2, ZnS, CdWO4, and ZnWO4 nanowires have been grown by this route. To the best of our knowledge, this is the first time that the synthesis of GaP and InP nanowires in aqueous solution has been achieved. This strategy is expected to extend to grow nanowires of other materials in solution or by vapor transport routes, since the nanowire growth of any inorganic materials can be realized by selecting an appropriate reaction and its corresponding lamellar inorganic,surfactant precursors. [source] Influence of wurtzite,zinc-blende interfacial energy on growth and crystal phase of the III-V nanowiresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010Maxim Lubov Abstract Influence of wurtzite,zinc-blende energy on nucleation rate and growth kinetics is studied. The physical model of III-V nanowires growth is proposed. We show that wurtzite,zinc-blende interfacial energy caused formation of the zinc-blende structure on the initial stage of nanowires growth. Role of the fluctuations in quasi-periodic crystal structure formation representing alternating layers of wurtzite and zinc-blende phase is revealed. Calculations of the growth of the nanowire growth accounting fluctuations in the droplet alloy are carried out. The results of the calculations are in a good agreement with available experimental data. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||