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

Silicon carbide (SiC) is a newly-emerging wide bandgap semiconductor, by which high-voltage, low-loss power devices can be realized owing to its superior properties. Because of its strong bonding energy and thermal stability, however, special cares must be paid to form high-quality junctions by ion implantation. This paper reviews present status and remaining issues of ion implantation technology in SiC. Requirements of hot implantation and high-temperature annealing are discussed in terms of electrical activation, defect generation, and junction characteristics. Furthermore, recent progress in junction termination for high-voltage SiC devices by using ion implantation is described.

Ion implantation technology in SiC for power device applications

Conductivity Control of SiC by In-Situ Doping and Ion Implantation

This paper evaluates the capability of SiC devices for operation under extremely high ambient temperatures. To this end, the authors packaged SiC JFET and Schottky barrier diodes (SBD) in thermally stable packages and built a high-temperature inductor to be evaluated in a DC-DC buck converter. The DC characteristics of the SiC JFET devices were first measured at ambient temperatures ranging from room temperature up to 450 degC. The experimental results show that the device can operate at 450 degC, which is impossible for conventional Si devices, but as expected the current capability of the SiC JFET diminishes with rising temperatures. A DC-DC converter was then designed and built in accordance with the static characteristics of the SiC JFETs that were measured under extremely high ambient temperatures. The converter was tested up to an ambient temperature of 400 degC. The conduction loss of the SiC JFET increases slightly, as predicted from its DC characteristics, but its switching characteristics hardly change with increasing temperatures. Thus, SiC devices are well suited for operation in harsh temperature environments

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Power Conversion with SiC Devices at Extremely High Ambient Temperatures

In this brief, the influence of high-density traps at the SiO2/SiC interface on short-channel effects was investigated, and a model describing channel length dependence of the threshold voltage (i.e., the gate voltage at a given drain current) is proposed. First, we determined the densities of interface states and fixed charge in 4H-SiC n-channel MOSFET by fitting the calculated gate characteristics to the experimental data, and acquired the density of trapped electrons from the obtained results. Then, we calculated the threshold voltage by considering that the majority of the trapped electrons are emitted near the drain end due to formation of a depletion layer. The channel length dependence of the threshold voltage calculated by the proposed model showed a good agreement with the experimental results even when the definition of threshold voltage was changed. The present model taking account of the fixed charge and of the trapped electron charge enables the estimation of the threshold voltage in the 4H-SiC short-channel MOSFETs.

Estimation of Threshold Voltage in SiC Short-Channel MOSFETs

The expansion/contraction behavior of single Shockley-type stacking faults (1SSFs) in 4H-SiC crystals is investigated by using an electronic energy model. The model takes into account several factors that were not considered in the previous models and provides a guideline to understand the 1SSF behavior. The authors calculated the threshold excess carrier density, which is the critical excess carrier density for the expansion/contraction of a 1SSF, for two models: with and without carrier recombination at a 1SSF. In the case of the model without carrier recombination, the obtained threshold excess carrier density at room temperature was at least 1 × 10 17 c m − 3. On the other hand, the threshold excess carrier density at room temperature given by the model with carrier recombination was in the range of 2 × 10 14 to 2 × 10 16 c m − 3, which shows good agreement with the previous experimental results quantitatively. The authors also discuss the temperature-, doping-concentration-, and conduction-type-dependences of the threshold excess carrier density. The calculated doping-concentration- and conduction-type-dependences of the threshold excess carrier density imply that the 1SSF expansion easily occurs in the heavily-doped crystals, and n-type 4H-SiC is slightly less tolerant against bipolar degradation than the p-type one.

Tsunenobu Kimoto

Papers

Ion implantation technology in SiC for power device applications

Conductivity Control of SiC by In-Situ Doping and Ion Implantation

Power Conversion with SiC Devices at Extremely High Ambient Temperatures

Estimation of Threshold Voltage in SiC Short-Channel MOSFETs

Electronic energy model for single Shockley stacking fault formation in 4H-SiC crystals