Papers by Keyword: Aluminium Oxide

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Authors: V.A. Skuratov, S.M. Abu-Al Azm, V.A. Altynov
Authors: Nur Ubaidah Saidin, Kuan Ying Kok, Inn Khuan Ng
Abstract: This paper reports on the process developed to fabricate anodic aluminum oxide (AAO) templates suitable for the fabrication of nanowires arrays. Anodization process has been used to fabricate the AAO templates with pore diameters ranging from 15 nm to 30 nm. Electrodeposition of parallel arrays of high aspect ratio nickel nanowires were demonstrated using these fabricated AAO templates. The nanowires produced were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the orientations of the electrodeposited nickel nanowires were governed by the deposition current and electrolyte conditions.
Authors: Shiro Hino, Tomohiro Hatayama, Jun Kato, Naruhisa Miura, Tatsuo Oomori, Eisuke Tokumitsu
Abstract: 4H-SiC MOSFETs with Al2O3/SiC and Al2O3/SiOx/SiC gate structures have been fabricated and characterized. Al2O3 was deposited by metal-organic chemical vapor deposition (MOCVD) and the SiOx layer was formed by dry-O2 oxidation. Insertion of 1.2 nm-thickness-SiOx layer drastically improves the channel mobility of Al2O3/SiC-MOSFET and anomalously high field effect mobility (μFE) of 284 cm2/Vs was obtained. The μFE of Al2O3/SiOx/SiC-MOSFET with various SiOx thickness was investigated, and it was found that insertion of a thin SiOx layer (< 2 nm) followed by the low temperature deposition of Al2O3 results in Al2O3/SiOx/SiC-MOSFET with such a high channel mobility.
Authors: Mika Vähä-Nissi, Terhi Hirvikorpi, Jenni Sievänen, Katriina Matilainen, Erkki Salo, Ali Harlin
Abstract: Biopolymers play still a relatively minor role in the packaging material markets. For this to grow further there are problems to be solved, such as inadequate barrier properties and moisture sensitivity. Atomic layer deposition (ALD) is one potential solution. Atomic layer deposition is a layer-by-layer thin film deposition process based on self-limiting gas-solid reactions. It is well suited for producing pinhole free barrier coatings uniform in thickness at relatively mild process conditions. The purpose of this presentation is to summarize our recent work done concerning atomic layer deposition of thin aluminum oxide layers onto biopolymers.
Authors: Kenichi Suzuki, Yuichiro Kuroki, Tomoichiro Okamoto, Masasuke Takata
Abstract: Alpha aluminum oxide (α-Al2O3) ceramics was coupled and reacted with zinc oxide (ZnO) ceramics at 1200°C for 24 h. Energy dispersive X-ray spectroscopy (EDS) analysis revealed the existence of step-shaped distribution of Al and Zn near the interface between α-Al2O3 and ZnO. Intense ultraviolet (3.75 eV) emission was clearly observed from the layer. On the other hand, very weak emissions were observed outside the layer near the interface. The compound in the layer is considered to be an attractive material for ultraviolet optoelectronics.
Authors: Kenichi Suzuki, Yuichiro Kuroki, Tomoichiro Okamoto, Masasuke Takata
Abstract: Zinc oxide (ZnO) ceramics was coupled and reacted with alpha aluminum oxide (α-Al2O3) ceramics at 1200oC for 24 h. SEM observation and energy dispersive X-ray spectroscopy (EDS) analysis revealed the existence of diffusion layer of 10 μm thickness on the α-Al2O3 side of interface between ZnO and α-Al2O3. The diffusion layer is considered to consist of a ZnAl2O4, from the result of XRD. The cathodoluminescence of the diffusion layer was compared with that of zinc aluminate (ZnAl2O4) ceramics synthesized by conventional solid state reaction method. The single phase ZnAl2O4 showed weak emission peaked at 4.6 eV. On the other hand, the diffusion layer showed intense emission peaked at 3.75 eV. The ZnAl2O4 on the α-Al2O3 side of the interface synthesized by coupling of ZnO and α-Al2O3 is considered to be a excellent material as an ultraviolet light emitter.
Authors: Xiao Bo Li, Hao Zheng, Ran Liu, Ge Yu Liang
Abstract: Liver is a major target of nanoparticles accumulation. Here we have analyzed the liver function and activation of liver macrophages, which are sensitive to alteration of liver internal environment after repeated exposure to aluminum oxide nanoparticles. Sprague-Dawley rats where intraperitoneally injected very two days for 60 dyas with aluminum oxide nanoparticles (50mg/kg), non-nanoaluminum oxide (50mg/kg) and saline. After 60 days exposure, the concentrations of alanine aminotransferase and aspartic transaminase in plasma were significantly higher in nanoaluminum oxide group than non-nanoaluminum oxide and control groups. The number of ED-1+ and GFAP+ cells in liver of nanoaluminum oxide and non-nanoaluminum oxide groups increased significantly than control group. Compared with non-nanoaluminum oxide, aluminum oxide nanoparticles display potential adverse effects on the hypatocytes and biliary tract of rat liver and less stimulus to macrophages in liver than non-nanoaluminum oxide. It is suggested that part aluminum oxide nanoparticles avoided from phagocytosis by liver macrophages. The effects of aluminum oxide nanoparticles exposure should be assessed for its potential hepatic toxicology.
Authors: Wojciech Gebarowski, Stanislaw Pietrzyk, Maria Richert
Abstract: The Plasma Electrolytic Oxidation (PEO) is a surface modification process that allows producing protective oxide coatings on light metal alloys. These coatings are characterized by high microhardness and wear resistance. Changes of electrical conditions of alternate current during process, such as duration and frequency of anodic and cathodic pulses, influence on layer growth rate, its microstructure and final properties. In this study aluminium samples were oxidized at different electrical parameters in sodium silicate electrolyte. The growth rates of oxide layers were determined by mass change and thickness measurements. The microstructure of the obtained coatings was investigated by using scanning electron microscope. Additionally, phase compositions of coatings was determined by X-ray diffraction on top surfaces of layers. Generally, shorter duration and higher frequency of anodic pulses provides more uniform structure at lower growth rate. Nevertheless, there are certain ranges of electrical parameters that provide decent uniformity of oxide coatings.
Authors: Maciej Wolborski, Mietek Bakowski, Viljami Pore, Mikko Ritala, Markku Leskelä, Adolf Schöner, Anders Hallén
Abstract: Aluminium oxide and titanium oxide films were deposited using the Atomic Layer Deposition method on n-type 4H SiC and p-type Si {001} substrates, with doping 6×1015cm-3 and 2×1016cm-3, respectively, and on 1.2 kV PiN 4H SiC diodes for passivation studies. The Al2O3 and SiC interface was characterised for the existence of an effective negative charge with a density of 1×1012-2×1012 cm-2. The dielectric constant of Al2O3 as determined from capacitance-voltage data was about 8.3. The maximum electric field supported by the Al2O3 film was up to 7.5 MV/cm and 8.4 MV/cm on SiC and Si, respectively.
Authors: H. Aoki, N. Komatsu, M. Honjo, K. Masumoto, C. Kimura, T. Sugino
Abstract: A gate insulator film with a wide bandgap and a high dielectric constants required to achieve high power field effect transistor (FET) using wide bandgap semiconductors such as SiC and diamond. We can achieve to suppress the gate leakage current and the charge shifts by using the AlSiO film. We found that the leakage current of Nitrogen-doped AlSiO film can be suppressed in high temperature region compared with AlSiO film. In addition, we attempted to study Yttrium aluminate (YAlO) and Lanthanum aluminate (LaAlO) as a gate insulator film. Since the Y (+3) and La(+3) have the same valence as Al (+3), it is expected that there is an advantage that Y, La doping generates less dangling bonds in the Al2O3 film. We can achieve to form aluminum based oxide film with higher dielectric constant by doping Lanthanoid atoms such as Y and La. The optimized YAlO and LaAlO films were applied to SiC-MIS structure. The Lanthanoid and Aluminum based oxide films can readily be applicable to wide bandgap semiconductor devices.
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