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

In the present study, we characterize the nature of interface states in silicon carbide (SiC) metal–oxide–semiconductor (MOS) systems by analyzing the electrical characteristics of MOS field effect transistors (MOSFETs) based on the results of numerical calculations. In the calculation, the potential distributions and energy sub-bands were calculated by solving Poisson and Schrodinger equations, respectively. As a result, we demonstrate that the defect-induced localized levels in the bandgap are subjected to quantum confinement at the inversion layer, leading to the increase in their energy levels. The result implies that the conventional interface defects (e.g., near-interface oxide traps), which create defect states at certain energy levels measured from the vacuum level, are unlikely to be the major origin of the interface states in SiC MOS systems. The interface state density is almost uniquely determined by the oxide formation process (as oxidation or interface nitridation) and independent of the acceptor concentration (3 × 1015–1 × 1018 cm−3). It is also suggested that the drain current decrease observed in heavily doped MOSFETs is mainly due to the decrease in the drift mobility rather than that in the free carrier density.

Effect of quantum confinement on the defect-induced localized levels in 4H-SiC(0001)/SiO2 systems

SiC bipolar junction transistors (BJTs) were fabricated based on the design criterion proposed in our previous study, which quantitatively proved the importance of decreasing a base spreading resistance. To reduce the base spreading resistance, Al+-implantation was performed in the parasitic base region. No negative influences due to the implantation damage on the current gain were confirmed when the implantation is performed sufficiently apart from the emitter mesa sidewall, the distance of which is longer than ${3}~\mu \text{m}$ . Since the fabricated BJTs satisfied the design criterion, clear conductivity modulation was achieved, resulting in a reduced collector-resistance, that is, 50% of the unipolar resistance. In addition, we experimentally demonstrated that the conductivity modulation in SiC BJTs could be enhanced by decreasing the base spreading resistance.

Demonstration of Conductivity Modulation in SiC Bipolar Junction Transistors With Reduced Base Spreading Resistance

Surface polarity dependence in step-controlled epitaxy: progress in SiC epitaxy

Fourier transform infrared (FT-IR) spectra were measured for thermal oxides with different electrical properties grown on 4H-SiC substrates. The peak frequency of the transverse optical (TO) phonon mode was blue-shifted by 5 cm-1 as the oxide-layer thickness decreased to 3 nm. The blue shift of the TO mode indicates interfacial compressive stress in the oxide. Comparison of data for the oxide on a SiC substrate with that for similar oxides on a Si substrate implies that the peak shift of the TO mode at the SiO2/SiC interface is larger than that of SiO2/Si, which suggests that the interfacial stress for the oxide on the SiC substrate is larger than that on the Si substrate. For the SiO2/SiC interfacial region (<3 nm oxide thickness), despite the fact that the blue shift of the TO modes becomes larger while approaching the oxide/SiC interface, the peak frequency of the TO modes red-shifts at the oxide/SiC interface. The peak-frequency shift of the TO mode for the sample without post-oxidation annealing was larger than that for the samples post-annealed in a nitric oxide atmosphere. The channel mobilities are correlated with the degree of shift of the TO mode when the oxide thickness is <3 nm. It appears that the compressive stress at the SiO2/SiC interface generates silicon suboxide components and weakens the Si-O bonds. As the result, the TO mode was red-shifted and the oxygen deficiency increased to relax the compressive stress in the oxide with <3 nm thickness. Fourier transform infrared spectroscopy measurements provide unique and useful information about stress and inhomogeneity at the oxide/SiC interface.

Tsunenobu Kimoto

Papers

Effect of quantum confinement on the defect-induced localized levels in 4H-SiC(0001)/SiO2 systems

Demonstration of Conductivity Modulation in SiC Bipolar Junction Transistors With Reduced Base Spreading Resistance

Surface polarity dependence in step-controlled epitaxy: progress in SiC epitaxy

Characterization of Thermal Oxides on 4H-SiC Epitaxial Substrates Using Fourier-Transform Infrared Spectroscopy.

Optical Properties of Silicon Carbide: Some Recent Developments