Cathodic electrodeposition from aqueous solution of dense or open‐structured zinc oxide films
About: This article is published in Advanced Materials.The article was published on 1996-02-01. It has received 506 citations till now. The article focuses on the topics: Zinc & Aqueous solution.
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TL;DR: Light emitting diodes based on n-ZnO nanorods combined with different technologies (hybrid technologies) are suggested and the recent electrical, as well as electro-optical, characteristics of these LEDs are shown and discussed.
Abstract: Zinc oxide (ZnO), with its excellent luminescent properties and the ease of growth of its nanostructures, holds promise for the development of photonic devices. The recent advances in growth of ZnO nanorods are discussed. Results from both low temperature and high temperature growth approaches are presented. The techniques which are presented include metal?organic chemical vapour deposition (MOCVD), vapour phase epitaxy (VPE), pulse laser deposition (PLD), vapour?liquid?solid (VLS), aqueous chemical growth (ACG) and finally the electrodeposition technique as an example of a selective growth approach. Results from structural as well as optical properties of a variety of ZnO nanorods are shown and analysed using different techniques, including high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), photoluminescence (PL) and cathodoluminescence (CL), for both room temperature and for low temperature performance. These results indicate that the grown ZnO nanorods possess reproducible and interesting optical properties. Results on obtaining p-type doping in ZnO micro-?and nanorods are also demonstrated using PLD. Three independent indications were found for p-type conducting, phosphorus-doped ZnO nanorods: first, acceptor-related CL peaks, second, opposite transfer characteristics of back-gate field effect transistors using undoped and phosphorus doped wire channels, and finally, rectifying I?V characteristics of ZnO:P nanowire/ZnO:Ga p?n junctions. Then light emitting diodes (LEDs) based on n-ZnO nanorods combined with different technologies (hybrid technologies) are suggested and the recent electrical, as well as electro-optical, characteristics of these LEDs are shown and discussed. The hybrid LEDs reviewed and discussed here are mainly presented for two groups: those based on n-ZnO nanorods and p-type crystalline substrates, and those based on n-ZnO nanorods and p-type amorphous substrates. Promising electroluminescence characteristics aimed at the development of white LEDs are demonstrated. Although some of the presented LEDs show visible emission for applied biases in excess of 10 V, optimized structures are expected to provide the same emission at much lower voltage. Finally, lasing from ZnO nanorods is briefly reviewed. An example of a recent whispering gallery mode (WGM) lasing from ZnO is demonstrated as a way to enhance the stimulated emission from small size structures.
606 citations
TL;DR: In this paper, illustrative examples to highlight the potential application of electrogeneration of base, anodic oxidation, and ac (alternating current) synthesis provide simple and inexpensive alternative routes to the synthesis of ceramic thin films and coatings.
Abstract: Emerging electrosynthetic techniques such as electrogeneration of base, anodic oxidation, and ac (alternating current) synthesis provide simple and inexpensive alternative routes to the synthesis of ceramic thin films and coatings, nanoparticulate materials, and metastable phases. In this review, we survey illustrative examples to highlight the potential application of these techniques in meeting the goals of inorganic solid-state synthesis.
561 citations
TL;DR: A superhydrophobic ZnO thin film fabricated by the Au-catalyzed chemical vapor deposition method shows good stability and durability and exhibits hierarchical structure with nanostructures on sub-microstructures.
Abstract: A superhydrophobic ZnO thin film was fabricated by the Au-catalyzed chemical vapor deposition method. The surface of the film exhibits hierarchical structure with nanostructures on sub-microstructures. The water contact angle (CA) was 164.3°, turning into a superhydrophilic one (CA < 5°) after UV illumination, which can be recovered through being placed in the dark or being heated. The film was attached tightly to the substrate, showing good stability and durability. The surface structures were characterized by scanning electron microscopy and atomic force microscopy.
469 citations
TL;DR: Some of the most common chemical and vapor-deposition methods for the synthesis of semiconductor metal oxide based detectors for chemical gas sensors are presented and a direct comparison of structural and chemical properties with sensing performance is given.
Abstract: Since the development of the first chemoresistive metal oxide based gas sensors, transducers with innovative properties have been prepared by a variety of wet- and dry-deposition methods. Among these, direct assembly of nanostructured films from the gas phase promises simple fabrication and control and with the appropriate synthesis and deposition methods nm to μm thick films, can be prepared. Dense structures are achieved by tuning chemical or vapor deposition methods whereas particulate films are obtained by deposition of airborne, mono- or polydisperse, aggregated or agglomerated nanoparticles. Innovative materials in non-equilibrium or sub-stoichiometric states are captured by rapid cooling during their synthesis. This Review presents some of the most common chemical and vapor-deposition methods for the synthesis of semiconductor metal oxide based detectors for chemical gas sensors. In addition, the synthesis of highly porous films by novel aerosol methods is discussed. A direct comparison of structural and chemical properties with sensing performance is given.
464 citations
TL;DR: In this paper, an overview of the evolutions of electrodeposition of semiconductors, as a function of time and material category (IV, III-V, II-VI), is given.
392 citations
References
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3,408 citations
TL;DR: In this paper, the authors described the highest efficiency single junction thin-film cell reported to date with an active area efficiency of 14.8% with the cell structure n−ZnO/n−CdS/p−CuInSe2 deposited on a soda-lime glass substrate.
Abstract: An important milestone in the development of photovoltaic thin‐film solar cells is the achievement of 15% conversion efficiency. This letter describes the highest efficiency single junction thin‐film cell reported to date. An active area efficiency of 14.8% is obtained with the cell structure n‐ZnO/n‐CdS/p‐CuInSe2 deposited on a soda‐lime glass substrate. The current achievements are due to improved properties of the CuInSe2 layer and the heterojunctions compared to previously reported results. The rate and substrate temperature profiles used during the coevaporation process yield a relatively large‐grained material with very strong 〈112〉 orientation and low porosity. This results in reduced recombination rates, hence higher open circuit voltage and fill factor.
455 citations
TL;DR: In this paper, the growth of vapor-deposited Cu overlayers on a ZnO(0001) (O face) single crystal has been investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectrography (AES), He + ion scattering spectroscope (ISS) and low-energy electron diffraction (LEED).
151 citations
TL;DR: In this paper, the authors generalized the theory of average dielectric constant developed by Genzel and Martin to the case of randomly oriented ellipsoidal particles having anisotropic Dielectric constants and incorporated effects which result from the mixture of different types of particles.
Abstract: Theory of average dielectric constant developed by Genzel and Martin is generalized to the case of randomly oriented ellipsoidal particles having anisotropic dielectric constants Effects which result from the mixture of different types of particles are also incorporated in the theory The generalized theory is applied to the calculation of infrared absorption spectra of ZnO small particles The present calculation can reproduce fairly well the experimental spectra of ZnO smoke reported by Yamamoto et al
111 citations
TL;DR: In this article, a transparent conducting films of cadmium stannate (Cd2SnO4), zinc oxide, and aluminum-doped zinc oxide have been made by a simple, economical electroless deposition technique.
Abstract: Transparent conducting films of cadmium stannate (Cd2SnO4), zinc oxide, and aluminum‐doped zinc oxide have been made by a simple, economical electroless deposition technique. The as‐deposited films of cadmium stannate have a 75% transmittance in the visible, 48% reflectance in the IR, and a band gap of 2.7 eV. Its resistivity is ∼10−1 Ω cm. Vacuum annealing changes the transmittance in the visible range to 82%, the IR reflectance to 62%, and the band gap to 3.1 eV. The corresponding values for the hydrogen‐annealed films are 87%, 76%, and 3.2 eV. Annealing lowers the resistivity of the films to ∼10−2 and ∼10−3 Ω cm for vacuum and hydrogen‐annealed films, respectively. The undoped zinc oxide films have transmittance in the visible and reflectance in the IR of 80 and 67% respectively. Aluminum doping increases the transmittance to 88% and reflectance to 83%. The optical band gap of undoped and aluminum‐doped zinc oxide films are found to be 3.40 and 3.98 eV, respectively. The resistivity is 1.20×10−2 and 6....
110 citations