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

The growth mechanism in chemical vapor deposition (CVD) of silicon carbide (SiC) on off-oriented SiC{0001} substrates (step-controlled epitaxy) is reviewed. In step-controlled epitaxy, SiC growth is controlled by the diffusion of reactants in a stagnant layer. Critical growth conditions where the growth mode changes from step-flow to two-dimensional nucleation are predicted as a function of growth conditions using a model describing SiC growth on vicinal {0001} substrates. Step bunching on the surfaces of SiC epilayers is also investigated. Dominant step heights correspond to the half or full unit cell of SiC polytypes. The high quality of the SiC epilayers has been elucidated through Hall effect and deep level measurements. Excellent doping controllability in a wide range has been obtained by in-situ doping of a nitrogen donor and an aluminum acceptor.

Step‐Controlled Epitaxial Growth of High‐Quality SiC Layers

Step bunching in chemical vapor deposition of 6H– and 4H–SiC on off-oriented {0001} faces is investigated with cross-sectional transmission electron microscopy. On an off-oriented (0001)Si face, three Si–C bilayer-height steps are the most dominant on 6H–SiC and four bilayer-height steps on 4H–SiC. In contrast, single bilayer-height steps show the highest probability on a (0001)C face for both 6H– and 4H–SiC epilayers grown with a C/Si ratio of 2.0. The increase of C/Si ratio up to 5.0 induces the formation of multiple-height steps even on a C face. The bunched step height corresponds to the unit cell or the half unit cell of SiC. The mechanism of step bunching is discussed with consideration of surface formation processes.

Step bunching mechanism in chemical vapor deposition of 6H– and 4H–SiC{0001}

Effects of wet atmosphere during oxidation and anneal on thermally oxidized p-type and n-type MOS interface properties were systematically investigated for both 4H- and 6H-SiC. Deep interface states and fixed oxide charges were mainly discussed. The wet atmosphere was effective to reduce a negative flatband shift caused by deep donor-type interface states in p-type SiC MOS capacitors. Negative fixed charges, however, appeared near the interface during wet reoxidation anneal. In n-type SIC MOS capacitors, the flatband shift indicated a positive value when using wet atmosphere. The relation between interface properties and characteristics of n-channel planar 6H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs) was also investigated. There was little relation between the interface properties of p-type MOS capacitors and the channel mobility of MOSFETs. The threshold voltage of MOSFETs processed by wet reoxidation anneal was higher than that of without reoxidation anneal. A clear relation between the threshold voltage and the channel mobility was observed in MOSFETs fabricated on the same substrate.

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Effects of wet oxidation/anneal on interface properties of thermally oxidized SiO/sub 2//SiC MOS system and MOSFET's

High-dose phosphorus-ion (P+) implantation into 4H–SiC (0001) followed by high-temperature annealing has been investigated. Annealing with a graphite cap largely suppressed the surface roughening of implanted SiC. The surface stoichiometry of implanted SiC was examined by x-ray photoelectron spectroscopy. Electronic behaviors of P+-implanted SiC are discussed based on Hall effect measurements. There is no significant difference in the sheet resistance between SiC annealed with a graphite cap and without a graphite cap. The sheet resistance (resistivity) takes a minimum value of 45 Ω/□ (0.9 mΩcm) at an implant dose of 6.0×1016 cm−2. The sheet resistance shows a weak temperature dependence.

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Electronic behaviors of high-dose phosphorus-ion implanted 4H-SiC(0001)

Deep levels in n-type 4H-SiC epilayers have been investigated by deep level transient spectroscopy (DLTS). The Z1∕2 and EH6∕7 centers are dominant in as-grown samples. After electron irradiation at 116 keV, by which only carbon atoms may be displaced, the Z1∕2 and EH6∕7 concentrations are significantly increased. The Z1∕2 and EH6∕7 centers are stable up to 1500–1600 °C and their concentrations are decreased by annealing at 1600–1700 °C. In the irradiated samples, the trap concentrations of the Z1∕2 and EH6∕7 centers are increased with the 0.7 power of the electron fluence. The concentrations of the Z1∕2 and EH6∕7 centers are very close to each other in all kinds of samples, as-grown, as-irradiated, and annealed ones, even though the condition of growth, irradiation (energy and fluence), and annealing has been changed. This result suggests that both Z1∕2 and EH6∕7 centers microscopically contain the same defect such as a carbon vacancy.

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Tsunenobu Kimoto

Papers

Step‐Controlled Epitaxial Growth of High‐Quality SiC Layers

Step bunching mechanism in chemical vapor deposition of 6H– and 4H–SiC{0001}

Effects of wet oxidation/anneal on interface properties of thermally oxidized SiO/sub 2//SiC MOS system and MOSFET's

Electronic behaviors of high-dose phosphorus-ion implanted 4H-SiC(0001)

Investigation of deep levels in n-type 4H-SiC epilayers irradiated with low-energy electrons