ZnO Arrays Research Articles

Highly Oriented Plate-like Rod/Tube Arrays of ZnO

Highly oriented plate-like rod/tube arrays of ZnO are synthesized by a solution-based approach at low temperature. The ZnO rod/tube arrays grow oriented vertically on silicon substrate and the intersectant ZnO nanosheets stand on the backbones of ZnO rods/tubes. The constructions of plate-like rod or tube arrays depend on the processing conditions. The growth mechanisms are investigated based on the nucleation and growth process. The initial ZnO film formed on substrate is crucial for the growth of ZnO rods/tubes perpendicular to the substrate. The nanosheets grow around the ZnO rods/tubes by the secondary nucleation and growth process. The ZnO tubes are formed by the etching of the ZnO polar faces. The novel ZnO structures are expected to have great potential for electronics, photoelectronics, sensors, and catalysis etc.

ZnO Light-Emission Array Fabricated into Nanometer-scale Pits on Silicon Substrate

ABSTRACTA nanometer-scale ZnO light emission array device was fabricated using the multi-level metallization technique of the CMOS process. Square arrays of pits with an inverted pyramid shape made from {111}Si planes were formed on a (100)Si substrate using selective etching. ZnO was deposited on the substrate by chemical vapor deposition (CVD), and the surface of the deposited ZnO film was carefully polished by chemical mechanical planarization (CMP). As a result, ZnO-filled nanometer-scale arrays were obtained after removing the ZnO layer except for the ZnO in the pits by CMP. Cathodoluminescence (CL) from the ZnO arrays was observed.

Fabrication of Nanodot Arrays on Si by Pulsed Laser Deposition Using Anodic Aluminum Oxide Nanopore Membrane as Mask

We demonstrate the fabrication of metal and semiconductor nanodot arrays on Si by pulsed laser deposition using an anodic alumina membrane as a mask. A Hexagonal-close-packed nanopore membrane mask was fabricated by the anodic oxidation of aluminum sheet. Pulsed laser deposition of Ag, Ni, ZnO, and Er-doped Si (Si:Er) nanodots was performed on a Si substrate to which an alumina membrane mask adheres by van der Waals interaction. Highly ordered arrays of Ag, Ni, ZnO, and Si:Er nanodots with average diameters ranging from 55 to 86 nm and a periodicity of ∼100 nm were obtained. Also, the time-resolved images of laser-produced plasma plumes were analyzed to examine the dynamical properties of the ejected materials.

Photoluminescence behavior of purpose-built ZnO arrays on different growth substrates

We fabricated purpose-built ZnO arrays directly on ITO conductive glass and in nanochannels of polycarbonate membrane, and investigated their photoluminescence properties. The former sample exhibited only two peaks at 360 and 390 nm, which correspond to the recombination of e–h+, and UV band emission, which confirms minimal defects existed. After annealing, the second kind of samples showed an additional two peaks, located at 488 and 540 nm. This fact may be explained by the defects in the newly formed ZnO, which is derived from Zn2+ adsorbed on the surface of the ZnO nanoparticles in the nanochannel.

Preparation of porous polymer membranes using nano- or micro-pillar arrays as templates

ZnO or polystyrene (PS) pillar arrays were formed on solid substrates and used as templates for the formation of porous polymer membranes. The membranes were formed by casting a polymer solution in the inter-pillar space of these templates and evaporating the solvent. Dissolution of the pillars in a selective solvent resulted in thin films containing monodisperse micrometer-sized channels. Membranes produced using the pillar template technique showed high water permeability and high size selectivity.

Large-Scale Fabrication of Tower-like, Flower-like, and Tube-like ZnO Arrays by a Simple Chemical Solution Route

Large-scale arrayed ZnO crystals with a series of novel morphologies, including tower-like, flower-like, and tube-like samples, have been successfully fabricated by a simple aqueous solution route. The morphology and orientation of the obtained ZnO crystal arrays can be conveniently tailored by changing the reactants and experimental conditions. For example, the tower-like ZnO crystal arrays were obtained in a reaction solution system including zinc salt, ammonia, ammonium salt, and thiourea, and the orientation of these tower-like crystals could be controlled by the contents of these reactants. Flower-like ZnO arrays were obtained at lower temperatures, and tube-like ZnO arrays were obtained by ultrasonic pretreatment of the reaction system. The growth mechanism of the tower-like and tube-like ZnO crystals was investigated by FESEM. The results show that tower-like crystals grow layer by layer, while tube-like crystals grow from active nanowires. Ultrasonic pretreatment is proved to be effective in promoting the formation of active nuclei, which have important effects on the formation of the tube-like ZnO crystals. In addition, large-scale arrays of these ZnO crystals can be successfully synthesized onto various substrates such as amorphous glass, crystalline quartz, and PET. This implies this chemical method has a wide application in the fabrication of nano-/microscale devices.

Self-Assembled Nanowire−Nanoribbon Junction Arrays of ZnO

We report the synthesis and characterization of nanowire−nanoribbon junction arrays of ZnO, which were grown by thermal evaporation of the mixture of ZnO and SnO2 powders at 1300 °C through a vapor−liquid−solid process. The Sn particles produced by the reduction of SnO2 act as the catalyst; the structure is formed due to a fast growth of ZnO nanowires along [0001] and the subsequent “epitaxial” radial growth of the ZnO nanoribbons along the six 〈011̄0〉 directions around the nanowire. The “liana” shape nanostructure could be a candidate for fabricating ultrahigh sensitive sensors.

Effect of colloid characteristics on the fabrication of ZnO nanowire arrays by electrophoretic deposition

In this study ZnO colloidal suspensions with varied characteristics were synthesized by varying the amount of added sodium hydroxide. The template-mediated preparation for nanosized ZnO arrays was conducted by electrophoretic deposition in the nanochannels of anodic alumina membranes. The effect of colloid characteristics on the deposition of ZnO nanowire arrays was investigated, and the related deposition mechanisms, morphologies and optical properties of the deposits were discussed. The deposited ZnO nanoarrays were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) studies. It was found that both the morphology and the deposition rate of ZnO nanowire arrays were influenced by the pH of the suspension and the applied voltage. The particle surface charge and size changed with the pH of the suspension, which in turn affected the deposition characteristics. The deposition rate of nanowire arrays was high at the initial stage and then approached a saturation value. The deposition rate also increased with increasing zeta potential of the particles and the applied voltage for EPD of ZnO nanowires. The photoluminescence properties of ZnO arrays were largely determined by particle size and surface properties of the nanoparticles comprising the nanowire arrays.

Preparation of Nanosized ZnO Arrays by Electrophoretic Deposition

We report a novel method for preparing uniform and aligned ZnO nanowire arrays embedded in anodic alumina membranes (AAM) by electrophoretic deposition (EPD). An integrated process combining the preparation of nanometer-sized ZnO particles and the formation of nanosized ZnO arrays by EPD within AAM was reported for the first time. The deposited nanowire arrays were characterized in terms of X-ray diffractometer, scanning electron microscope, and photospectrometer. As compared with other methods for the preparation of nanowire arrays, the proposed method is simple, materials general, and efficient.

Preparation and characterization of nanosized ZnO arrays by electrophoretic deposition

We report a novel method for preparing uniform and aligned ZnO nanowire arrays embedded in anodic alumina membranes by electrophoretic deposition (EPD). The effects of colloidal concentration and heat treatment on the characteristics of ZnO arrays are investigated. X-ray diffraction, scanning electron microscopy (SEM), ultraviolet visible (UV–VIS) spectrophotometry were employed. Highly aligned ZnO arrays have been successfully prepared using this method. The results show that with an increase in the colloidal concentration the growth rate will be decreased, while the crystallite size will be enhanced. The spectroscopic result indicates that a blue shift can be observed. The effect of heat treatment can result in the sharpening of XRD peak for ZnO.

3D Highly Oriented Nanoparticulate and Microparticulate Array of Metal Oxide Materials

AbstractAdvanced nano and micro particulate thin films of 3d transition and post-transition metal oxides consisting of nanorods and microrods with parallel and perpendicular orientation with respect to the substrate normal, have been successfully grown onto various substrates by heteronucleation, without template and/or surfactant, from the aqueous condensation of solution of metal salts or metal complexes (aqueous chemical growth). Three-dimensional arrays of iron oxide nanorods and zinc oxide nanorods with parallel and perpendicular orientation are presented as well as the oxygen K-edge polarization dependent x-ray absorption spectroscopy (XAS) study of anisotropic perpendicularly oriented microrod array of ZnO performed at synchrotron radiation source facility.