다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

A Survey of Wide Bandgap Power Semiconductor Devices

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

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Light-emitting diodes

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

We formed a low-resistance p region by high-dose aluminum (Al) ion implantation in the 4H-SiC (0001) face, and fabricated and characterized planar pn diodes by Al or boron (B) ion implantation. In Al ion implantation, the minimum sheet resistance of 3.6 kω/□ (p-type) is obtained by high-temperature implantation and high-temperature annealing. Excellent rectification was verified in planar pn diodes, in which the surface p+ layer was formed by high-temperature implantation of Al ions and the p layer was formed by room-temperature implantation of high-energy B ions. We achieved a high blocking voltage of 2900 V (90% of the theoretical withstand voltage), a low on-resistance of 8.0 mωcm2, and avalanche breakdown characteristics of a positive temperature coefficient for the blocking voltage. We fabricated a 4H-SiC (1120) pn diode, which has not been disclosed previously, and obtained a high blocking voltage of 1850 V (70% of the theoretical blocking voltage). © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(12): 44–51, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10162

High-Voltage 4H-SiC pn Diodes Fabricated by p-Type Ion Implantation

Dislocations in 4H-SiC epilayers were imaged nondestructively by means of micro photoluminescence (-PL) mapping at room temperature. The one-to-one correspondence between the individual dislocations and the -PL mapping contrast has been consistently obtained. By analyzing the reduction of the intensity in the -PL mapping image performed at 390 nm (near band-edge emission), we were able to distinguish threading screw dislocations and threading edge dislocations. Furthermore, the contrast of dislocations in PL-intensity mapping image greatly depends on the carrier lifetimes of the 4H-SiC epilayers. Lifetimes longer than 0.5 s are essential to obtain a discernible contrast for the individual dislocations.

Impact of Carrier Lifetimes on Non-Destructive Mapping of Dislocations in 4H-SiC Epilayers

We studied the photoluminescence (PL) spectrum and dynamics of highly dense electron–hole (\(e\)–\(h\)) systems of the wide- and indirect-gap semiconductor 4H-SiC. PL spectra near the critical temperature were complicated owing to excitons, \(e\)–\(h\) liquids, and \(e\)–\(h\) plasmas. We found that the PL from \(e\)–\(h\) liquids shows a rise time of several tens of picoseconds. From the \(e\)–\(h\) density and temperature dependence of the time-resolved PL spectra, we determined the phase diagram of the \(e\)–\(h\) system in 4H-SiC, which includes excitons, \(e\)–\(h\) liquids, and \(e\)–\(h\) plasmas.

Determination of Phase Diagram of Electron-Hole Systems in 4H-SiC

Homoepitaxial growth, impurity doping, and diode fabrication on 4H-SiC(11–20) and (03–38) have been investigated. Although the efficiency of nitrogen incorporation is higher on the non-standard faces than on (0001), a low background doping concentration of 2∼3×1014 cm-3 can be achieved. On these faces, boron and aluminum are less effectively incorporated, compared to the growth on off-axis (0001). 4H-SiC(11–20) epilayers are micropipe-free, as expected. More interestingly, almost perfect micropipe closing has been realized in 4H-SiC (03–38) epitaxial growth. Ni/4H-SiC(11–20) and (03–38) Schottky barrier diodes showed promising characteritics of 3.36 kV-24 mΩcm2 and 3.28 kV–22 mΩcm2, respectively. The breakdown voltage of 4H-SiC(03–38) Schottky barrier diodes was significantly improved from 1 kV to above 2.5 kV by micropipe closing.

Epitaxial Growth and Characterization of 4H-SiC(11–20) and (03–38)

Recent progress in horaoepitaxial growth of 6H-SiC by stop-controlled epitaxy utilizing off-angle substrates is discussed in detail. Features of step-controlled epitaxy and its growth mechanism are described based on experimental results. The growth mode on off-angle substrates is explained by a stagnant layer model. The diffusion length of adatoms on a surface is calculated using a simple surface diffusion model. The critical conditions of two-dimensional nucleation and step-flow growth are predicted based on theoretical calculation and experimental results. Microscopic surface processes such as nucleation and step motion are made clear by observing the grown layer after short-time growth.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400408080

Tsunenobu Kimoto

Papers

High-Voltage 4H-SiC pn Diodes Fabricated by p-Type Ion Implantation

Impact of Carrier Lifetimes on Non-Destructive Mapping of Dislocations in 4H-SiC Epilayers

Determination of Phase Diagram of Electron-Hole Systems in 4H-SiC

Epitaxial Growth and Characterization of 4H-SiC(11–20) and (03–38)

Nucleation and Step Dynamics in SIC Epitaxial Growth