Download or read book Electronic structure of Al doped ZnO transparent conductive thin films studied by x ray absorption and emission spectroscopies written by 邱昭文 (物理學) and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book From Molecules to Materials written by Elena A. Rozhkova and published by Springer. This book was released on 2015-04-06 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This interdisciplinary book focuses on the various aspects transformation of the energy from sunlight into the chemical bonds of a fuel, known as the artificial photosynthesis, and addresses the emergent challenges connected with growing societal demands for clean and sustainable energy technologies. The editors assemble the research of world-recognized experts in the field of both molecular and materials artificial systems for energy production. Contributors cover the full scope of research on photosynthesis and related energy processes.
Download or read book Transparent Conductive Zinc Oxide written by Klaus Ellmer and published by Springer Science & Business Media. This book was released on 2007-12-29 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) belongs to the class of transparent conducting oxides that can be used as transparent electrodes in electronic devices or heated windows. In this book the material properties of, the deposition technologies for, and applications of zinc oxide in thin film solar cells are described in a comprehensive manner. Structural, morphological, optical and electronic properties of ZnO are treated in this review.
Download or read book Characterization of Aluminum Doped Zinc Oxide Thin Films for Photovoltaic Applications written by Bojanna P. Shantheyanda and published by . This book was released on 2010 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing demand for clean source of energy in the recent years has increased the manufacture of solar cells for converting sun energy directly into electricity. Research has been carried out around the world to make a cheaper and more efficient solar cell technology by employing new architectural designs and developing new materials to serve as light absorbers and charge carriers. Aluminum doped Zinc Oxide thin film, a Transparent conductive Oxides (TCO) is used as a window material in the solar cell these days. Its increased stability in the reduced ambient, less expensive and more abundance make it popular among the other TCO's. It is the aim of this work to obtain a significantly low resistive ZnO:Al thin film with good transparency. Detailed electrical and materials studies is carried out on the film in order to expand knowledge and understanding. RF magnetron sputtering has been carried out at various substrate temperatures using argon, oxygen and hydrogen gases with various ratios to deposit this polycrystalline films on thermally grown SiO2 and glass wafer. The composition of the films has been determined by X-ray Photoelectron Spectroscopy and the identification of phases present have been made using X-ray diffraction experiment. Surface imaging of the film and roughness calculations are carried out using Scanning Electron Microscopy and Atomic Force Microscopy respectively. Determination of resistivity using 4-Probe technique and transparency using UV spectrophotometer were carried out as a part of electrical and optical characterization on the obtained thin film. The deposited thin films were later annealed in vacuum at various high temperatures and the change in material and electrical properties were analyzed.
Download or read book Atom Probe Tomography written by Williams Lefebvre and published by Academic Press. This book was released on 2016-05-30 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atom Probe Tomography is aimed at beginners and researchers interested in expanding their expertise in this area. It provides the theoretical background and practical information necessary to investigate how materials work using atom probe microscopy techniques, and includes detailed explanations of the fundamentals, the instrumentation, contemporary specimen preparation techniques, and experimental details, as well as an overview of the results that can be obtained. The book emphasizes processes for assessing data quality and the proper implementation of advanced data mining algorithms. For those more experienced in the technique, this book will serve as a single comprehensive source of indispensable reference information, tables, and techniques. Both beginner and expert will value the way the book is set out in the context of materials science and engineering. In addition, its references to key research outcomes based upon the training program held at the University of Rouen—one of the leading scientific research centers exploring the various aspects of the instrument—will further enhance understanding and the learning process. - Provides an introduction to the capabilities and limitations of atom probe tomography when analyzing materials - Written for both experienced researchers and new users - Includes exercises, along with corrections, for users to practice the techniques discussed - Contains coverage of more advanced and less widespread techniques, such as correlative APT and STEM microscopy
Download or read book Polymers for Light emitting Devices and Displays written by Inamuddin and published by John Wiley & Sons. This book was released on 2020-05-27 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers for Light-Emitting Devices and Displays provides an in-depth overview of fabrication methods and unique properties of polymeric semiconductors, and their potential applications for LEDs including organic electronics, displays, and optoelectronics. Some of the chapter subjects include: • The newest polymeric materials and processes beyond the classical structure of PLED • Conjugated polymers and their application in the light-emitting diodes (OLEDs & PLEDs) as optoelectronic devices. • The novel work carried out on electrospun nanofibers used for LEDs. • The roles of diversified architectures, layers, components, and their structural modifications in determining efficiencies and parameters of PLEDs as high-performance devices. • Polymer liquid crystal devices (PLCs), their synthesis, and applications in various liquid crystal devices (LCs) and displays. • Reviews the state-of-art of materials and technologies to manufacture hybrid white light-emitting diodes based on inorganic light sources and organic wavelength converters.
Download or read book Electronic and Optical Properties of Oxide Thin Films written by Steven Daniel Kirby and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Off-axis sputtering has been used to study two oxide thin film systems. The first study involved developing an epitaxially grown NiO/SrTiO3 heterostructure to be used for a negative index of refraction. The second used off-axis sputtering as a combinatorial approach to study the effects of doping and codoping of transparent conducting ZnO. A negative index of refraction should be possible by combining only intrinsic material resonances. We proposed that combining NiO, which has an antiferromagnetic resonance in the far infrared, and SrTiO3, which has a dielectric resonance in the far-infrared, can be used to achieve a negative refractive index of refraction in the far-infrared. These resonances can be shifted through changing temperature, doping, or through applying a magnetic field. A high quality epitaxially grown composite heterostructure and bulk ceramics have been fabricated. Preliminary measurements of the permeability and permittivity been taken for a bulk composite structure. The SrTiO3 ionic resonance can be seen in a reflection technique while the NiO antiferromagnetic resonance is easily seen in a transmission technique ZnO is a potential inexpensive replacement for indium tin oxide (ITO) as a high-end transparent conductor. However, ZnO has not replaced ITO in many applications such as flat-panel displays due to high resistivity and poor thermal stability. ZnO has been doped with many elements including Al, In and Ga. We proposed that codoping with both Al and In might result in size compensation which would lead to improved dopant solubility and therefore better electrical conductivity and stability. A high-throughput combinatorial approach was used to study codoping of ZnO with both Al and In. Measurement of the deposited composition spread suggests that codoping results in much improved conductivity. By adding 1% In to highly Al-doped ZnO (3-6%) the conductivity increases by an order of magnitude. Thermal annealing in a variety of atmospheres including air, vacuum and hydrogen results in some understanding of the difference in the two dopants. It was found that Al doping results in a higher carrier concentration than In doping, but any excess Al greatly decreases the mobility. In doping improves the mobility but with lower carrier concentrations. Calculations based on density functional theory support the experimental data, showing that Al is a shallower dopant than In. Unit cell volume comparisons between theory and experiment correspond well. The interplay between substitutional doping, oxygen vacancies, and possible adventitious H doping makes the doped ZnO system difficult to analyze definitively.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2018 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deposition of Al doped ZnO Films by High Power Impulse Magnetron Sputtering written by Martin Mickan and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transparent conducting oxides (TCOs) are an important class of materials with many applications such as low emissivity coatings, or transparent electrodes for photovoltaics and flat panel displays. Among the possible TCO materials, Al-doped ZnO (AZO) is studied due to its relatively low cost and abundance of the raw materials. Thin films of AZO are commonly produced using physical vapour deposition techniques such as magnetron sputtering. However, there is a problem with the homogeneity of the films using reactive direct current magnetron sputtering (DCMS). This homogeneity problem can be related to the bombardment of the growing film with negative oxygen ions, that can cause additional acceptor defects and the formation of insulating secondary phases. In this work AZO films are deposited by high power impulse magnetron sputtering (HiPIMS), a technique in which high instantaneous current densities are achieved by short pulses of low duty cycle. In the first part of this thesis, the possibility to improve the homogeneity of the deposited AZO films by using HiPIMS is demonstrated. This improvement can be related to the high instantaneous sputtering rate during the HiPIMS pulses, so the process can take place in the metal mode. This allows for a lower oxygen ion bombardment of the growing film, which can help to avoid the formation of secondary phases. Another problem of AZO is the stability of the properties in humid environments. To assess this problem, the degradation of the electrical properties after an aging procedure was investigated for films deposited by both DCMS and by HiPIMS. A method was proposed, to restore the properties of the films, using a low temperature annealing under N2 atmosphere. The improvement of the electrical properties of the films could be related to a diffusion process, where water is diffusing out of the films. Then, the influence of the substrate temperature on the properties of AZO films deposited by HiPIMS was studied. The electrical, optical and structural properties were found to improve with increasing substrate temperature up to 600° C. This improvement can be mostly explained by the increase in crystalline quality and the annealing of defects. Finally, the deposition of AZO films on flexible PET substrates was investigated. The films are growing as a thick porous layer of preferentially c-axis oriented columns on top of a thin dense seed layer. The evolution of the sheet resistance of the films after bending the films with different radii was studied. There is an increase in the sheet resistance of the films with decreasing bending radius, that is less pronounced for thicker films.
Download or read book Spectroscopic Ellipsometry written by Hiroyuki Fujiwara and published by John Wiley & Sons. This book was released on 2007-09-27 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ellipsometry is a powerful tool used for the characterization of thin films and multi-layer semiconductor structures. This book deals with fundamental principles and applications of spectroscopic ellipsometry (SE). Beginning with an overview of SE technologies the text moves on to focus on the data analysis of results obtained from SE, Fundamental data analyses, principles and physical backgrounds and the various materials used in different fields from LSI industry to biotechnology are described. The final chapter describes the latest developments of real-time monitoring and process control which have attracted significant attention in various scientific and industrial fields.
Download or read book Fundamental Understanding of the Growth Doping and Characterization of Aligned ZNO Nanowires written by Gang Shen and published by . This book was released on 2014 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) is a II-VI semiconductor whose wide direct bandgap (3.37 eV) and large exciton binding energy (60 meV) make it compelling for optoelectronic devices such as light emitting diodes, lasers, photodetectors, solar cells, and mechanical energy harvesting devices. One dimensional structures of ZnO (nanowires) have become significant due to their unique physical properties arising from quantum confinement, and they are ideal for studying transport mechanisms in one-dimensional systems. In this doctoral research work, ZnO nanowire (NW) arrays were synthesized on sapphire substrates through carbo-thermal reduction of ZnO powders, and the effects of growth parameters on the properties of ZnO NW arrays were studied by scanning and transmission electron microscopy, X-ray diffraction, photoluminescence and Raman spectroscopy. Based on the phonon mode selection rules in wurtzite ZnO, confocal Raman spectroscopy was used to assess the alignment of ZnO NWs in an array, thereby complementing X-ray diffraction. Al doped ZnO NW arrays were achieved by mixing Al powder into the ZnO and graphite source mixture, and the presence of Al was confirmed by Energy-dispersive X-ray spectroscopy. The incorporation of Al had the effects of lowering the electrical resistivity, slightly deteriorating crystal quality and suppressing defect related green emission. Two models of ZnO NW growth were developed by establishing the relationship between NW length and diameter for undoped and Al doped ZnO NWs separately. The growth of undoped ZnO NWs followed the diffusion-induced model which was characterized by thin wires being longer than thick wires, while the growth of Al doped ZnO was controlled by Gibbs-Thomson effect which was characterized by thin wires being shorter than thin wires. Local electrode atom probe analysis of ZnO NWs was carried out to study the crystal stoichiometry and Al incorporation. Undoped ZnO NWs were found to be high purity with no detectable impurities. Possible Al incorporation related peaks were observed in the mass spectrum of Al doped ZnO NWs. Further work on Al doped ZnO LEAP analysis is needed to better understand the Al dopant.
Download or read book Relationship Between Structure and Magnetic Behaviour in ZnO Based Systems written by Clara Guglieri Rodríguez and published by Springer. This book was released on 2015-06-03 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work studies the magnetic behavior of ZnO nanoparticles capped with different organic molecules and showing room-temperature ferromagnetism (RTFM). Of particular significance is the combination of element-specific X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) techniques, which demonstrates the intrinsic occurrence of RTFM in these systems and indicates that it is not related to the 3-D states of the metallic cation but is relayed along the conduction band of the semiconductor. The discovery of room-temperature ferromagnetism (RTFM) in semiconductors holds great promise in future spintronics technologies. Further results presented here include O K-edge XMCD studies, which demonstrate that the oxygen ions have a ferromagnetic response in these ZnO-based systems, providing the first direct support for claims regarding the appearance of oxygen ferromagnetism in oxide semiconductors at the nanoscale.
Download or read book Impact of Air exposure on the Chemical and Electronic Structure OfZnO written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemical and electronic surface structure of ZnO:Zn3N2 ("ZnO:N") thin films with different N contents was investigated by soft x-ray emission spectroscopy. Upon exposure to ambient air (in contrast to storage in vacuum), the chemical and electronic surface structure of the ZnO:N films changes substantially. In particular, we find that the Zn3N2/(Zn3N2+ZnO) ratio decreases with exposure time and that this change depends on the initial N content. We suggest a degradation mechanism based on the reaction of the Zn3N2 content with atmospheric humidity.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Doping in Zinc Oxide Thin Films written by Zheng Yang and published by . This book was released on 2009 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Doping in zinc oxide (ZnO) thin films is discussed in this dissertation. The optimizations of undoped ZnO thin film growth using molecular-beam epitaxy (MBE) are discussed. The effect of the oxygen ECR plasma power on the growth rate, structural, electrical, and optical properties of the ZnO thin films were studied. It was found that larger ECR power leads to higher growth rate, better crystallinity, lower electron carrier concentration, larger resistivity, and smaller density of non-radiative luminescence centers in the ZnO thin films. Low-temperature photoluminescence (PL) measurements were carried out in undoped and Ga doped ZnO thin films grown by molecular-beam epitaxy. As the carrier concentration increases from 1.8 x 10 to 1.8 x 10 cm -3, the dominant PL line at 9 K changes from I 1 (3.368 - 3.371 eV), to I DA (3.317 - 3.321 eV), and finally to I 8 (3.359 eV). The dominance of I, due to ionized donor bound excitons, is unexpected in n-type samples, but is shown to be consistent with the temperature-dependent Hall fitting results. We also show that I DA has characteristics of a donor acceptor pair transition, and use a detailed, quantitative analysis to argue that it arises from Ga Zn donors paired with Zn-vacancy (V Zn) acceptors. In this analysis, the Ga Zn 0/+ energy is well-known from two-electron satellite transitions, and the V Zn 0/- energy is taken from a recent theoretical calculation. Typical behaviors of Sb-doped p -type ZnO are presented. The Sb doping mechanisms and preference in ZnO are discussed. Diluted magnetic semiconducting ZnO:Co thin films with above room-temperature T C were prepared. Transmission electron microscopy and x-ray diffraction studies indicate the ZnO:Co thin films are free of secondary phases. The magnetization of the ZnO:Co thin films shows a free electron carrier concentration dependence, which increases dramatically when the free electron carrier concentration exceeds ~10 19 cm -3, indicating a carrier-mediated mechanism for ferromagnetism. The anomalous Hall effect was observed in the ZnO:Co thin films. The anomalous Hall coefficient and its dependence on longitudinal resistivity were analyzed. The presence of a side-jump contribution further supports an intrinsic origin for ferromagnetism in ZnO:Co thin films. These observations together with the magnetic anisotropy and magnetoresistance results, supports an intrinsic carrier-mediated mechanism for ferromagnetic exchange in ZnO:Co diluted magnetic semiconductor materials. Well-above room temperature and electron-concentration dependent ferromagnetism was observed in n -type ZnO:Mn films, indicating long-range ferromagnetic order. Magnetic anisotropy was also observed in these ZnO:Mn films, which is another indication for intrinsic ferromagnetism. The electron-mediated ferromagnetism in n -type ZnO:Mn contradicts the existing theory that the magnetic exchange in ZnO:Mn materials is mediated by holes. Microstructural studies using transmission electron microscopy were performed on a ZnO:Mn diluted magnetic semiconductor thin film. The high-resolution imaging and electron diffraction reveal that the ZnO:Mn thin film has a high structual quality and is free of clustering/segregated phases. High-angle annular dark field imaging and x-ray diffraction patterns further support the absence of phase segregation in the film. Magnetotransport was studied on the ZnO:Mn samples, and from these measurements, the temperature dependence of the resistivity and magnetoresistance, electron carrier concentration, and anomalous Hall coefficient of the sample is discussed. The anomalous Hall coefficient depends on the resistivity, and from this relation, the presence of the quadratic dependence term supports the intrinsic spin-obit origin of the anomalous Hall effect in the ZnO:Mn thin film.
Download or read book Transparent Conductive Materials written by David Levy and published by John Wiley & Sons. This book was released on 2019-04-29 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by well-known pioneers in the field, this handbook and ready reference provides a comprehensive overview of transparent conductive materials with a strong application focus. Following an introduction to the materials and recent developments, subsequent chapters discuss the synthesis and characterization as well as the deposition techniques that are commonly used for energy harvesting and light emitting applications. Finally, the book concludes with a look at future technological advances. All-encompassing and up-to-date, this interdisciplinary text runs the gamut from chemistry and materials science to engineering, from academia to industry, and from fundamental challenges to readily available applications.
Download or read book Ceramic Abstracts written by and published by . This book was released on 1998 with total page 1040 pages. Available in PDF, EPUB and Kindle. Book excerpt:
