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Plasmon gain by core-level electrons or elastic electrons observed in past studies seems to be of no practical value in material characterization, mainly because of their ultralow signal intensities. Nevertheless, in the emission spectra of Au samples, we have observed plasmon gain in secondary electrons. The electrons gain energy from surface plasmons after escaping from the surface and thereby only carry surface-plasmon information in the vacuum above the surface. Because the intensity of the emitted SEs is strong, rivaling that of core-level or elastic electrons, the observed phenomenon has in practice the potential to image directly in space the surface plasmon near but exterior to the metal surface.

We fabricated successfully heterostructures of AlGaN/GaN and AlGaN/InGaN/GaN on AlN template/c-sapphire exhibiting the Shubnikov-de Haas (SdH) oscillation in the magnetic field at lower temperatures. In AlxGa1-xN/GaN system, the carrier density of two-dimensional electron gas (2DEG) was controlled from 4.0 × 1012 to 9.0 × 1012 cm−2, which was consistent with the theoretical simulation, with increase of Al composition in AlGaN barrier layer. In AlGaN/InGaN/GaN system, the surface morphology and alloy disorder on the InGaN were properly defined. The effective mass of 2DEG at the Al0.22Ga0.78N/In0.04Ga0.96N interface was estimated to be 0.24 m0 from the temperature dependence of SdH oscillation amplitude. Although the effective mass was comparable to that of AlGaN/GaN heterostructure, the mobility of 2DEG at the InGaN was drastically degraded in spite of the slight amount of indium incorporation. This reduction was attributed to larger scattering probably due to the interface roughness of InGaN layer caused by the step meandering and/or the potential fluctuation caused by random incorporation of indium atoms.

The National Institute for Materials Science, Japan, has been developing a materials data platform linked with a materials data repository system for rapid new material searching using materials informatics. Data conversion from raw data to a human-legible/machine-readable data file is one of the key preparation techniques prior to data analysis, where the converted data file should include metainformation. The tools developed by the authors can convert raw data to a structured data package that consists of mandatory and measurement-characterization metadata, primary and raw parameters, and formatted numerical data (FND). The FND are expressed as a matrix type with robust flexibility. This flexibility is achieved by applying the data analysis architecture of schema-on-read, not schema-on-write based on de jure standards, such as ISO documents. The primary parameters are carefully selected from raw parameters, and their vocabularies are transformed from instrument-dependent terms to general terms that everyone can readily understand. The converted data are linked with, for example, specimen information, process information, specimen handling records, and the electronic laboratory notebook. Using this raw-to-repository (R2R) conversion flow, the authors demonstrated that they can generate and store interoperable data files of x-ray photoelectron spectroscopy (XPS) spectra and depth profiles, powder x-ray diffraction patterns, (scanning) transmission electron microscope images, transmission electron diffraction patterns, electron energy-loss spectroscopy spectra, and calculated electron inelastic mean free path data. Linking measurement data to other required information ensures experimentally repeatable, replicable, and reproducible results. The mandatory and characterization metadata are used for quick electronic searching, and primary and raw parameters are convenient for setting up measurement conditions and useful for reproducibility/replicability and replicability/repeatability, respectively. The FND are human legible and machine readable using parser software, leading to a long lifetime of data utilization. The authors also developed a system to allow the semiautomatic data transfer from an instrument-controlling personal computer (PC) isolated from the communication network by adopting a Wi-Fi-capable secure digital card’s scripting capability while keeping the PC offline. They are developing further software for on-demand data manipulation after R2R data conversion. To date, it has been possible to perform XPS peak separation using an automated information compression technique without any a priori assumption. By combining R2R conversion with a high-throughput data collection system and automated data analysis routine, highly reproducible data acquisition and data analysis could be achieved, where human interaction is minimized. At this early stage, the authors demonstrate automated peak separation processing for XPS C 1s and O 1s narrow spectra of polyethylene terephthalate with very high reproducibility.The National Institute for Materials Science, Japan, has been developing a materials data platform linked with a materials data repository system for rapid new material searching using materials informatics. Data conversion from raw data to a human-legible/machine-readable data file is one of the key preparation techniques prior to data analysis, where the converted data file should include metainformation. The tools developed by the authors can convert raw data to a structured data package that consists of mandatory and measurement-characterization metadata, primary and raw parameters, and formatted numerical data (FND). The FND are expressed as a matrix type with robust flexibility. This flexibility is achieved by applying the data analysis architecture of schema-on-read, not schema-on-write based on de jure standards, such as ISO documents. The primary parameters are carefully selected from raw parameters, and their vocabularies are transformed from instrument-dependent terms to general terms that ever...

c-plane ZnO films were eptiaxially grown on c-GaN/sapphire substrate by MOCVD. Cathodoluminescence (CL) line scan was performed on the cross-sectional ZnO/GaN films. These CL spectra shapes show a variation along the growth direction with a peak position shift, which can be divided into three stages. The study of the three stages reflects the growth mode alteration from the interface between ZnO and GaN to the surface. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Transport properties of the MgB 2 thin films on Si, MgO and ZnO substrates with Ti buffer layer prepared by molecular beam epitaxy were investigated to clarify effects of the substrates and the Ti buffer layer on flux pinning. The critical current density J c of each sample shows different dependence on magnetic fields parallel to c -axis. However, the scaling analysis of the macroscopic pinning force for all the measured samples implies that the grain boundaries work as the dominant pinning centers for B // c . The pinning parameter for MgB 2 /Ti/Si estimated from the electric field E vs. the current density J characteristics shows the highest value among all the measured samples. This result is attributed to the high density of grain boundaries caused by the effect of both the Ti buffer and Si substrate in the growth process. Therefore, the selection of substrates and buffer layer strongly affects the flux pining properties of MgB 2 thin films and plays an important role in the determination of performance for superconducting devices and wires.

Hydroxyapatite (HAp) coatings were directly formed on pure magnesium in aqueous solutions using C 10 H 12 CaN 2 Na 2 O 8 (Ca-EDTA) and KH 2 PO 4 . The influence of the treatment temperature and concentration of Ca-EDTA on the microstructure of the coatings was investigated. The growth of the HAp crystals was promoted with an increase in the treatment temperature. The growth direction of HAp crystals was along [002] HAp regardless of the treatment temperature, and the HAp crystals then showed a rod-like shape. The HAp crystals contained Na and Mg. A Mg(OH) 2 layer was formed between the HAp coating and the magnesium substrate above 363 K. With a decrease in the treatment time, the formation of the Mg(OH) 2 layer was suppressed. A dense and uniform HAp-coating layer was obtained without the formation of a Mg(OH) 2 intermediate layer by adjusting the treatment time and concentrations of calcium and phosphate species.

We designed a 5-GHz miniaturized 8-pole bandpass filter (BPF) using superconducting microstrip quasi-spiral resonators (QSRs) for international mobile telecommunication (IMT)-advanced receiving applications. We used the QSRs with line width and spacing equal to 10 μm for further miniaturization, and investigated a relationship between the structure of the QSR and the unloaded quality factor (Q u ). The Q u of the optimized QSR of approximately 25,000 was obtained. It was difficult to design a BPF using miniaturized QSRs with high Q u because of strong cross couplings between QSRs. The λ g /8-line inserted inverters were effective in decreasing the unwanted cross couplings. Using these QSR and the λ g /8-line inserted inverters, 8-pole cascaded quadruplet (CQ) BPF was designed. We found that it was possible to design a miniaturized BPF with high Q u .

We present experimental and calculated phase diagrams of the upper critical field Hc2 and the anisotropy parameter γ of various MgB2 thin films prepared by the molecular beam epitaxy (MBE) and the multiple-targets sputtering system. Experimental data of the Hc2(T) and γ are analyzed by fitting the Gurevich theory. We obtained the result that for these MgB2 films the Hc2(T) is explained as the case of Dπ/Dσ>1, which means the films are classified to the cleaner π band than the σ band. We discuss temperature dependence of the transition width obtained from the magnetoresistance measurements.

We designed a 5 GHz miniaturized 10-pole Chebyshev-type bandpass filter (BPF) using superconducting microstrip quasi-spiral resonators (QSR) for international mobile telecommunication (IMT)-advanced receiving applications. When we considered the unloaded quality factor (Qu) of QSR, we found that a 10-pole QSR BPF using single-sided films and a 17-pole QSR BPF using double-sided films can be achieved an insertion loss in simulation of than 0.5 dB. The 10-pole QSR filter was fabricated using a 300 nm thick single-sided MgB2 film on a c-sapphire substrate by a thermal co-evaporation method. The Au ground plane of the filter was deposited on the other side of the substrate. Simulation and measurement profile data obtained from the passband were in close agreement. We found that the power-handling performance was equivalent to that of other miniaturized filters. We could design multi-pole filters using QSR.

We report on the fabrication and properties of all-MgB 2 tunnel junctions with an MgO barrier. Superconductor–insulator–superconductor (SIS) junctions were fabricated on C -plane sapphire substrates. MgB 2 films were grown in an ultra-high vacuum in the 10 −9 Torr range. The MgO insulating layer was evaporated using an electron-beam gun. SIS junctions of 30 μm in diameter were fabricated by standard photolithography and Ar ion milling techniques. The critical temperature ( T C ) of the lower MgB 2 layer after the SIS junction fabrication process was 36.7 K, which remained the same as that of the bare MgB 2 film. We observed tunneling behavior in the current–voltage ( I–V ) characteristics of the present junctions. A superconducting gap was clearly observed at around 2.7 mV (=2 Δ ).

We report on the upper critical fields ( H c2 ’s) of as-grown MgB 2 thin films deposited on the epitaxial Ti buffer layer on c -plane ZnO substrates by using a molecular beam epitaxy (MBE) apparatus. The H c2 was estimated from the magnetoresistance measurements under the pulsed magnetic field up to 37 T. H c2 ( T ) for both H ∥ ab -plane and H ∥ c -axis were measured to obtain the anisotropic superconducting properties. The results are successfully analyzed with the Gurevich theory of dirty two-gap superconductivity with a cleaner π band case.

In this study, we have investigated the effects of Ti buffer layer for the fabrication of MgB2 crystalline film on ZnO (0001) substrate. The Ti buffer layers (thickness of 5-50 nm) and MgB2 films were deposited by molecular beam epitaxy apparatus. The MgB2/Ti bilayers were characterized by in-situ RHEED and ex-situ XRD measurements, and the superconducting properties were studied by magnetic measurements using SQUID magnetometer. It is found that Ti layers were grown epitaxially on the substrates and the MgB2 films were c-axis oriented with two types of in-plane rotational domains. The crystallinity reflected on the rocking curve width and the superconducting transition temperature Tc were enhanced with increasing the thickness of Ti buffer layer. The highest Tc in this study was obtained to be 37 K when the Ti buffer layer thickness is 50 nm.

We propose a miniaturized novel microstrip quasi-spiral resonator (QSR) system composed of rewound-type spiral resonator and c-type spiral resonator. We have also designed a 5 GHz superconducting 4-pole bandpass filter (BPF) using QSR for international mobile telecommunication (IMT)-advanced base station receiver applications. The filter has been fabricated using a single-sided MgB2 superconducting thin film deposited by thermal co-evaporation technique. The measured performance of the BPF has been found to show close agreement with the simulated one.

As-grown MgB2 thin films were prepared by a MBE method under the conditions of low temperature, low deposition rate and high vacuum for applications in electric devices. The MgB2 thin films deposited on MgO and Ti buffered ZnO substrates have considerably higher Jc under magnetic fields among MgB2 thin films reported before. The value of Jc for the MgB2 thin film deposited on Ti buffered ZnO has been 5.8 × 105 A cm−2 at 10 K, 5 T in the magnetic field applied parallel to the c axis. In the angular dependence of Jc, the peak of Jc attributable to c-axis-correlated pinning centres has been observed when the magnetic field was applied parallel to the c axis.

The intermetallic superconductor magnesium diboride (MgB 2 ) is a promising candidate for use in superconducting electronic devices because of its high transition temperature ( T c ). These applications require the development of a high-quality film fabrication process. We have previously reported the growth of MgB 2 films deposited on MgO (1 0 0), SrTiO 3 (1 0 0) and Al 2 O 3 (0 0 0 1) substrate using a co-evaporation method and molecular beam epitaxy (MBE) apparatus. In this paper, we will report the correlation between structural properties and physical properties of as-grown MgB 2 films deposited on MgO (1 0 0), ZnO (0 0 0 1), and Si (1 1 1) substrate. The films’ basal properties have been confirmed by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), resistivity measurements and SQUID magnetometry. The details of the interfacial structure were studied by transmission electron microscopy (TEM). We will then discuss the most important parameters for fabricating high quality as-grown MgB 2 films and junctions.

We have made as-grown MgB 2 film deposited by molecular beam epitaxy (MBE) under co-evaporation conditions of low temperature, low growth rate, and ultra high vacuum on three types of substrates, MgO(100), Al 2 O 3 (0001), and SrTiO 3 (100). The optimization of these conditions was investigated with respect to (1) growth temperature (T s < 250 °C), (2) B deposition rate, and (3) Mg/B deposition ratio. The film properties were investigated by RHEED, XRD, AFM, electrical'resistivity, and SQUID magnetometer. The film grown at 200 °C, B deposition rate of 0.3 A/s and Mg/B ratio of 8 showed the highest T c,onset of 35 K and had a sharp transition (ΔT c = 0.5 K). We report the upper critical field and anisotropy ratio of these films.

As-grown superconducting MgB_2 thin films have been grown on SrTiO_3(001), MgO(001), and Al_2O_3(0001) substrates by a molecular beam epitaxy (MBE) method with novel co-evaporation conditions of low deposition rate in ultra-high vacuum. The structural and physical properties of the films were studied by RHEED, XRD, electrical resistivity measurements, and SQUID magnetometer. The RHEED patterns indicate three-dimensional growth for MgB_2. The highest T_c determined by resistivity measurement was about 36K in these samples. And a clear Meissner effect below T_c was observed using magnetic susceptibility measurement. We will discuss the influence of B buffer layer on the structural and physical properties., Comment: 9 pages with 4 figures, ISS2003 proceeding

Electrical characteristics of leakage current paths in vertical-type n-GaN Schottky barrier diodes (SBDs) on free-standing GaN substrates are investigated by using photon emission microscopy (PEM). The PEM mapping shows that the initial failure of the SBD devices at low voltages is due to the leakage current paths from polygonal pits in the GaN epilayers. It is observed that these polygonal pits originate from carbon impurity accumulation to the dislocations with a screw-type component by microstructure analysis. For the SBD without polygonal pits, no initial failure is observed and the first leakage appeals at the edge of electrodes as a result of electric field concentration. The mechanism of leakage at pits is explained in terms of trap assisted tunneling through fitting current-voltage characteristics.

We studied the emissive pits in InGaN films grown on compressive and strain-free GaN underlying layers. Pit density decreased with the full width at half maximum of ω(0002) of InGaN. The films grew on compressive and strain-free GaN underlying layers with spiral and step-flow modes, respectively. Carbon impurities accumulated inside the pits. Comparison of cathodoluminescence inside the pits and steady-state photocapacitance spectra showed that the energy level of the carbon impurities appeared at ∼2.8 eV below the conduction band (Ec) for both types of pits. Deep-level defects at Ec −2.4 eV resulting in green fluorescence emission were considered to originate from pits related to screw dislocations.

We report that Ti buffer layer improves the structural quality and superconducting properties of MgB2 film deposited on ZnO (0 0 0 1) and Al2O3 (0 0 0 1) substrates using molecular beam epitaxy. It was found that Ti layers were grown epitaxially on the substrates and the MgB2 films were c-axis oriented with two types of in-plane orientations. The crystal quality measured by the rocking curve width of X-ray diffraction peak was improved and superconducting transition temperature increased as the buffer layer thickness increased on both substrates. The highest Tc observed in this study was 37 K and 35 K in the film deposited on the Ti buffer layer 50 nm thick with the ZnO and Al2O3 substrates, respectively.

We have measured the magnetic field dependence of the resistivity using a 35 T pulsed magnet for the as-grown MgB 2 films fabricated on the epitaxial Ti buffer layer grown on c -plane ZnO and Al 2 O 3 substrates by molecular beam epitaxy (MBE). We will report the upper critical fields ( H c 2 ) along H | | c -axis and H | | ab -plane. The anisotropy ratio were obtained from these H c 2 values. The effects of Ti buffer layer on the H c 2 and the anisotropy of MgB 2 film were discussed.

The intermetallic superconductor magnesium diboride (MgB2) is a promising candidate for use in superconducting electronic devices because its high transition temperature (Tc). These applications require the development of a high-quality film fabrication process. We report the first ever attempt to use ZnO (0 0 0 1) substrate to fabricate as-grown MgB2 films. The lattice mismatch between ZnO and MgB2 is smaller than for previous reported substrates. The structural and physical properties of the films were investigated by RHEED, XRD, XPS, and resistivity measurements. The resistivity measurements suggest the maximum transition temperature of these films to be 35 K; their resistivity at 300 K is 8.9 μΩ cm. Our results indicate that these films, when deposited on ZnO substrates, have potential for the fabrication of higher quality MgB2 films. We also investigate the growth temperature dependence and substrate dependence for superconductivity of MgB2 films. We discuss the most important conditions and the effectiveness of ZnO substrate for fabricating as-grown MgB2 films.

Superconducting thin films of magnesium diboride (MgB2) were prepared on MgO(0 0 1) substrate by molecular beam epitaxy in the co-evaporation conditions of low deposition rate and ultra-high vacuum. A superconducting transition with the onset temperature of 31.2 K was confirmed by both transport and magnetization measurements. The upper critical fields are obtained from measurement of the field dependence of the resistivity. It was estimated that the upper critical field at 0 K was more than 15 T. The upper critical field anisotropy ratio, H C 2 , ab ( 0 ) / H C 2 , c ( 0 ) , was estimated to be 1.78 from the magnetic field–temperature phase diagram for as-grown MgB2 thin films.

We demonstrate that a SiO disproportionation reaction can be achieved simply by high energy mechanochemical milling. The planetary ball-milling of ZrO2 for a few minutes generated Si nano-crystals. Milling conditions including rotation speed, ball number, milling time, and type of ball material were able to control the oxidation states of Si. The ball-milled SiO powder was tested as an anode of a lithium battery. ZrO2 contamination from the vial and balls was eliminated by dipping the ball-milled SiO powder in (NH4)HSO4 molten salt and heating for 5 min. The disproportionated SiO powder showed characteristics comparable to those of a powder prepared by a conventional heating process taking several hours.

The discovery of the superconductivity at a transition temperature (TC) of 39 K in magnesium diboride (MgB2) has attracted much attention from many researchers for scientific as well as technical reasons [1]. Compared with Cu-based superconductors (cuprates), MgB2 has lower anisotropy and larger coherence length, in addition to high Tc [2]. These characteristics of MgB2 give rise to new applications for superconductor devices that can operate in the temperature range between 20 and 30 K; examples of such devices are Josephson junctions and integrated circuits. This temperature range can be easily achieved by using economical and compact cryocoolers or liquid hydrogen. The use of cryocoolers may transform the superconductor from being specialized and advanced technology into common usage in consumer devices. In the future, hydrogen gas may be widely used for carbon-free power generation such as in fuel cells. Liquid hydrogen would be available for these purposes, and may be utilized for the cooling of low-temperature devices. In addition, MgB2 is considered to be a clean superconducting material, using neither toxic nor rare earth elements.

We present experimental results of the upper critical fields $H_{\rm c2}$ of various MgB$_2$ thin films prepared by the molecular beam epitaxy, multiple-targets sputtering, and co-evaporation deposition apparatus. Experimental data of the $H_{\rm c2}(T)$ are successfully analyzed by applying the Gurevich theory of dirty two-band superconductivity in the case of $D_{\pi}/D_{\sigma}>1$, where $D_{\pi}$ and $D_{\sigma}$ are the intraband electron diffusivities for $\pi$ and $\sigma$ bands, respectively. We find that the parameters obtained from the analysis are strongly correlated to the superconducting transition temperature $T_{\rm c}$ of the films. We also discuss the anormalous narrowing of the transition width at intermediate temperatures confirmed by the magnetoresistance measurements., Comment: 7 pages, 7 figures, submitted to Phys. Rev. B

The intermetallic superconductor MgB2 is one of the promising candidates for use in superconducting electronic devices because of its high critical temperature of 39K. The application requires the developments of a high‐quality film fabrication process. Recently we succeeded to deposit the as‐grown MgB2 films on MgO (100) substrates by using a molecular beam epitaxy (MBE) method. To evaluate the film property microscopically, the electric structure of the MgB2 films was studied by means of ultraviolet photoemission Spectroscopy (UPS). A clear peak was observed at 8–12 eV and 5–8eV binding energy corresponding to the B 2pσ and 2pπ derived state. These features are in good agreement with those of bulk MgB2 reported previously.

During the last 14 years, externally supported noncoated knitted Dacron grafts (EXS) and gelatin-coated knitted Dacron grafts with rings (GEL) were used in 176 patients for femoropopliteal bypass (F-P), femorofemoral bypass (F-F) and axillofemoral bypass (Ax-F). In the EXS group, 58 F-P above knee (ak), 42 below knee (bk), 25 F-F, and 19 Ax-F surgeries were performed. Twenty-three F-Pak, 5 F-Pbk, 26 F-F, and 8 Ax-F surgeries were performed in the GEL group. In the F-Pak, primary patency at 5 and 9 years was 75.5 and 53% for the EXS and that at 3 and 5 years was 75.0 and 60.0% for the GEL (n.s.). In the F-Pbk, primary patency at 5 and 10 years was 60.5 and 29.5% for the EXS, while patency at 1 year was 11.1% for the GEL (P0.05). In both the EXS and the GEL groups, the F-Pak surgery showed better outcomes than the F-Pbk surgery. The outcomes of the F-P grafts implanted into the legs with claudication were better than those performed for the limb salvage cases. Primary patency of the F-F and the Ax-F showed no differences and there were also no differences between the graft types. For F-Pak surgery, the EXS is the graft of choice. The GEL is not suitable for F-Pbk surgery. For F-F and Ax-F reconstruction, both the EXS and the GEL are acceptable.

We have grown FCC-Fe/Cu multilayers by molecular beam epitaxy method. The structural and magnetic properties were studied by RHEED, XRD and magnetoresistance measurement (MR). The RHEED images confirmed that Fe/Cu multilayers were epitaxially grown on Cu (1 0 0) . Furthermore, a clear negative MR was observed. The buffer layer condition for MR effect will be discussed.

We have investigated the structure and magnetic properties of Fe/Bi multilayers and trilayers by RHEED, XRD, XRR, XPS and SQUID. The samples were grown by molecular beam epitaxy method. It was found that the synthesis of the multilayer is very difficult. However, we successfully grown Fe/Bi trilayers by adopting the appropriate growth conditions.

As a next-generation memory, we have developed a rare-metal-free memory using Al oxide with a high-density of oxygen vacancies (Vos). The electronic structure has been simulated using first-principles calculations. In this paper, we report the electronic structure of the band gap, analyzed using thermally stimulated current measurements, to evaluate the simulated results. We observed electronic states corresponding to resistance changes for the first time. These results show that Vo+2 (electron empty Vo) changes to Vo+1 by electron injection; the overlapped Vo+1 electron changes into a “Vo conduction band” (VoCB), and the changed structure is stabilized by structural relaxation of Al ions around Vo. VoCB is considered as a kind of mid-gap impurity band. The origin of the on/off switching is considered to be generation/degeneration of the VoCB caused by increasing/decreasing numbers of Vo electrons. Based on knowledge of the electronic mechanism, we have changed metal/insulator/metal structure to a metal/i...