eprzekwa's nanocolumn_growth [20 articles]

Abstract

ZnO naorods on ZnO-coated seed substrates were fabricated by solution chemical method from Zn(NO3)2/NaOH under assisted electrical field. The working mechanism of electrical field was analyzed and the factors affecting the rod growth such as potential, precursor concentration and growth temperature were elucidated. The structural and optical properties are characterized by SEM, TEM, XRD, HRTEM and UV-vis. The results indicated that the nanorods have wurtzite structure without electrical field and are primarily of zincite structure under electrical field; when the electrical ...

Abstract

ZnO nanorods on ZnO-coated seed surfaces were fabricated by a solution chemical method using supersaturated Zn(NO3)2/NaOH solution. The seed surfaces were coated on glass substrates by sol-gel processing and PEG addition. The mechanism of crystal growth and the factors affecting the rod growth were elucidated. The morphology and structure of both the seed surface and successive nanorods were analyzed by using SEM, XRD, TEM and SAED. Nucleation on the ZnO seed surface is crucial for rod growth since rods can only ...

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Abstract: Nanoscale ZnO grains and rods having various aspect ratios were selectively synthesized through acidic and basic routes, respectively, in an aqueous system at 60 C. Equiaxial nanograins were obtained by the addition of NaOH into an acidic solution of ZnSO4 (acidic route). On the other hand, nanorods with an aspect ratio ~12 were prepared by the introduction of ZnSO4 into a basic solution of NaOH (basic route). The aspect ratio of ZnO nanoparticles was changed by the preparation routes, whereas ...

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Abstract: ZnO nanosheets, nanonails, and well-aligned nanorods were fabricated on Zn foils by a solvothermal approach using ethanol as the solvent. A lower synthesis temperature and a shorter time period favor the formation of nanosheets. By optimizing the synthesis temperature and time period, ZnO nanonails with a hexagonal cap and a long stem could be produced. A higher temperature was not favorable to produce uniform and smooth nanorods. Well-aligned ZnO nanorod arrays were produced with diameters within 100-250 nm and lengths ...

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Without using additional surfactant as structure-directing agent, well dispersed ZnO nanorods were directly synthesized in the dimethyl sulfoxide (DMSO) and alcohol mixture solution by a one-step wet chemical method. The experiment results demonstrated that alcohol molecular with longer chain is helpful for the growth of ZnO nanorods. The absorption and emission spectra of as-synthesized ZnO nanorods were also presented in this paper. ...

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The growth of ZnO nanorods on Au-coated ITO substrates using a low temperature wet chemical process is presented. Electron microscopy and x-ray diffraction observations reveal that the crystalline ZnO nanorods are preferentially oriented along the c axis. Room temperature photoluminescence (PL) measurements reveal a strong band edge emission at 382~nm, a signature of good crystallinity, with a weak and broad orange–red emission, which is typically attributed to the oxygen interstitials, in the range between 520 and 720~nm. Other than the second ...

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Well-aligned ZnO nanorod and nanopencil arrays were synthesized in a high density on ZnO/Si substrate by a low-temperature aqueous solution technique. Detailed structural characterizations revealed that the as-synthesized nanorods and nanopencils were single crystalline, with a hexagonal phase, and with growth along the [0001] direction. The room-temperature photoluminescence spectra showed a strong ultraviolet emission at 381~nm, a weak blue band at 460~nm, and a broad green emission at 580~nm. A detailed growth mechanism has been proposed for the formation of nanorods ...

Abstract

A simple method to fabricate the one-dimensional nanostructure of zinc oxide nanorods from aqueous solution was presented. ZnO nanorods, prepared under different concentrations of precursors, were characterized by techniques such as XRD and SEM. The results indicated that the ZnO nanorods were single crystalline and grown in the direction of [001] with the hexagonal wurtzite structure. Photoluminescence measurement of the ZnO nanorods was carried out and it showed that a strong near-band-gap emission dominated the PL spectra with several weak emission ...

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We report metalorganic vapor-phase epitaxial growth and structural and photoluminescent characteristics of ZnO nanorods. The nanorods were grown on Al2O3(00·1) substrates at 400 °C without employing any metal catalysts usually needed in other methods. Electron microscopy revealed that nanorods with uniform distributions in their diameters, lengths, and densities were grown vertically from the substrates. The mean diameter of the nanorods is as narrow as 25 nm. In addition, x-ray diffraction measurements clearly show that ZnO nanorods were grown epitaxially with homogeneous ...

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    4

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Abstract: Well-aligned ZnO nanorods with identical crystallographic orientation have been synthesized using a vapor transport deposition process. Orientation-ordered nanorods grow normal to the c planes of the as-deposited micrometer-sized ZnO rods on a polycrystalline Al2O3 substrate, and each nanorod is along [0001] and enclosed by 20 facet surfaces. The nanorods remain in an identical crystal orientation with a homoepitaxial orientation relationship with the microrod. During the synthesis, reduced Sn from SnO2 powder added to the source materials functions as a catalyst, ...

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Article #3

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This article surveys recent developments in the rational synthesis of single-crystalline zinc oxide nanowires and their unique optical properties. The growth of ZnO nanowires was carried out in a simple chemical vapor transport and condensation (CVTC) system. Based on our fundamental understanding of the vapor-liquid-solid (VLS) nanowire growth mechanism, different levels of growth controls (including positional, orientational, diameter, and density control) have been achieved. Power-dependent emission has been examined and lasing action was observed in these ZnO nanowires when the excitation ...

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Article 1

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Abstract: We are reporting here on the inexpensive fabrication of large three-dimensional and highly oriented porous microrod array of n-type ZnO semiconductor with a unique designed architecture consisting of well-defined, length-tailored, monodisperse, perpendicularly oriented single-crystalline hexagonal rods, grown directly onto polycrystalline, single-crystalline, or amorphous substrates, from an aqueous solution of zinc salt at low temperature. ...

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We have developed several methods to prepare nano-structured semiconductor and conducting oxide layers for large area applications. Due to their unique optical and electrical properties these layers have considerable potential for the fabrication of a novel solar cell type with an extremely thin absorber (eta-cell). Preparation methods, structural and optical properties are reported. ...

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Abstract: A method for growing vertical ZnO nanowire arrays on arbitrary substrates using either gas-phase or solution-phase approaches is presented. A ~10 nm-thick layer of textured ZnO nanocrystals with their c axes normal to the substrate is formed by the decomposition of zinc acetate at 200-350 C to provide nucleation sites for vertical nanowire growth. The nanorod arrays made in solution have a rod diameter, length, density, and orientation desirable for use in ordered nanorod-polymer solar cells. ...

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Electrodeposition of polycrystalline semiconductor thin films is mainly used for photovoltaic applications. Most of the work concerns chalcogenide compounds like CdTe, CuInSe2, CdS... This route is also emerging for semiconductor oxide preparation. Results concerning the electrodeposition of zinc oxide layers by reduction of dissolved oxygen in presence of Zn(II) ions are presented. Epitaxial growth can be achieved in zinc chloride solutions on single crystal GaN layers. Bandgap (Eg) variations and effects on photoluminescence are observed by changing the deposition conditions and ...

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another method for constructing nanowires, using a method of cathodic electrodeposition

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ZnO nanowires have been grown on sapphire and Si substrates using catalytic growth. A strong near-band-gap ultraviolet emission is observed at room temperature. By carefully studying the temperature dependence of ZnO wire emission, we found that the room-temperature UV emission contains two different transitions; one is related to the ZnO free exciton and the other is related to the free-to-bound transition. The bound state has a binding energy of about 124 meV. The results from optical measurements show that a high ...

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Here is a way to grow ZnO nano columns using complexing agents.

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A novel approach to the rational fabrication of smart and functional metal oxide particulate thin films and coatings is demonstrated on the growth of ZnO nanowires and oriented nanorod arrays. The synthesis involves a template-less and surfactant-free aqueous method, which enables the generation of, at large-scale, low-cost, and moderate temperatures, advanced metal oxide thin films with controlled complexity. The strategy consists of monitoring of the nucleation, growth, and aging processes by means of chemical and electrostatic control of the interfacial free ...

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Here is a solution method for creating ZnO nanocolumns. It is low cost, and low temp. It uses a thermal decomposition technique.

Abstract

Abstract: A new method of depositing expitaxial ZnO nanocolumns on sputter-coated ZnO substrates is described that utilizes supersaturated zincate species in sodium hydroxide solutions and requires no complexing agents. Uniform arrays of columns are grown reproducibly over entire substrates in 10-50 min. Columns are 50-2000 nm long and 50-100 nm wide. Strict substrate cleaning and/or preparation was not necessary with this method, in contrast to many other techniques, probably because the high pH generates a reproducible surface. The interfacial properties of ...

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Alternative Method to Dana Olson's