When aluminum nitride (AlN) thin films are applied to surface acoustic wave devices, (100) orientated films are necessary, because the electromechanical coupling coefficient of the (100) oriented ...films are superior to that of the (001) oriented films. However, it is hard to prepare the (100) oriented films by sputtering and ion plating. In this study, preferential orientation of AlN films was investigated. It was found that the (100) oriented films were deposited by the reactive DC magnetron sputtering method at a long distance (
L) between the Al target and substrate (above 120 mm) and at high sputtering pressures (above 0.6 Pa). According to our theory, the relative growth rate of (100)/(001) is varied by changing the deposition unit from atoms to a dimer such as Al–N. Namely, when the mean free path of Al and N is longer than the distance
L, Al and N atoms deposit directly on the substrate and the (001) oriented films grow. When it is shorter than the distance
L, the collisions of Al and N atoms occur in the space between the target and the substrate and the Al–N dimers are formed and deposit on the substrate. In this case, the (100) orientation is enhanced.
We upgraded the hard X-ray spectroscopy beamline BL39XU at SPring-8 by installing Kirkpatrick-Baez mirrors to equip it with submicron-focusing capability. At the new experimental end-station located ...74 m from the undulator source, an X-ray nanoprobe with a size of 120 × 100 nm2 has become available at 5–16 keV. This upgrade is fully compatible with the X-ray polarization tunability and helicity-switching between right- and left-circular polarizations; these are unique features of the beamline, which is equipped with a diamond X-ray phase retarder. A spatial resolution of ≈100 nm for X-ray absorption fine structure and X-ray magnetic circular dichroism (XMCD) spectroscopy has been achieved. We show a magnetization reversal process of an individual magnetic dot in bit-patterned perpendicular recording media using element-specific XMCD magnetization measurements to demonstrate the performance of the new station.
We developed micro-focusing Kirkpatrick-Baez (K-B) mirror optics for the X-ray free electron laser (XFEL) at the SPring-8 Angstrom Compact free electron Laser (SACLA) facility in Japan. The K-B ...focusing mirrors have a spatial acceptance of 600 × 600 μm2 and ultra-precision surfaces. A manipulator for precise alignment of the mirrors was also developed. The focusing properties for 10-keV X-rays were evaluated with a wire-scanning method. The focal beam size was determined to be 0.95 μm × 1.20 μm at the full width at half maximum. An increased power density of 1018 W/cm2 was achieved at the focal point. These properties were confirmed to be in good agreement with the designed value.
We present new diagnostics for use in optical laser pump - X-ray Free Electron Laser (XFEL) probe experiments to monitor dimensions, intensity profile and focusability of the XFEL beam and to control ...initial quality and homogeneity of targets to be driven by optical laser pulse. By developing X-ray imaging, based on the use of an LiF crystal detector, we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution (∼1 μm) and across a field of view larger than some millimetres. This diagnostic can be used in situ, provides a very high dynamic range, has an extremely limited cost, and is relatively easy to be implemented in pump-probe experiments. The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser (SACLA) XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.
We have developed a fast scanning microscopic X-ray absorption fine-structure (XAFS) measurement system using a 100–300 nm focused X-ray beam at the BL39XU nano-scale analysis station at SPring-8. ...This system provides two-dimensional XAFS images constructed from X-ray fluorescence (XRF) images measured by fast continuous 2-dimensional scanning at all XAFS measurement energies. High-quality XAFS spectra at each position were obtained by correcting shift in the XRF images. We applied our proposed method to measuring single catalyst particles, and succeeded in measuring the microscopic x-ray absorption near-edge structure (XANES) images that were 2–4 μm square with a spatial resolution of 300 nm.
We evaluated the ablation threshold of silicon and synthetic fused silica, which are widely used as optical substrates such as those in X-ray mirrors. A focusing XFEL beam with a beam size of ...approximately 1 μm at a photon energy of 10 keV was used. We confirmed that the ablation thresholds of these materials, which were 0.8 μJ/μm2 for the silicon and 4 μJ/μm2 for the synthetic fused silica, approximately agreed with the melting dose.
Application of ITO films to photocatalysis Yumoto, H.; Inoue, T.; Li, S.J. ...
Thin solid films,
05/1999, Letnik:
345, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
The concentration of NO
2 gas, an environmental pollutant, can be reduced by photocatalysis. A simple method for measuring the efficiency of photocatalysis is required. In general, the efficiency of ...photocatalysis is determined by measuring the decrease in the concentration of NO
2 gas during UV light irradiation. In this study, an NO
2 gas sensor made of ITO film was used to detect the photocatalytic oxidation of NO
2. When ZnO film prepared by electroplating was used as the photocatalyst, the photocatalytic reaction was measured continuously with good reproducibility, showing that this method is useful. Next, the photocatalyst was changed from ZnO to ITO film, and the photocatalytic efficiency was studied. ITO film composed of fine particles (30–60 nm), which was prepared by magnetron sputtering, had a very low efficiency. However, ITO film with ITO whiskers (30 nm in diameter and 500–700 nm in length) prepared by the electron shower method showed a similar high efficiency to ZnO film.
Optimization of focusing conditions is important in free-electron laser applications. A time-of-flight mass analyzer has been designed and constructed for this purpose. The time-of-flight spectra of ...ionic species evolved from laser ablation of gold were measured. The yields of ionic species showed strong correlations with free-electron-laser intensity. This method conveniently allows for direct estimation of laser intensity on sample and determination of focusing position.
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