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

Si-nanowire p-channel metal-oxide-semiconductor field effect transistors (MOSFETs), in which the typical cross section of the nanowire is a rectangular shape with 3 nm height and 18 nm width, have been fabricated and the current-voltage characteristics have been measured from 101 to 396 K. The transconductance has shown oscillation up to 309 K. The carrier transport has been theoretically analyzed, assuming that the acoustic phonon scattering is dominant. The electronic states have been determined from the effective mass approximation and the mobility from the relaxation time approximation as a function of the Fermi level. Relation between the gate voltage and the Fermi level has been estimated from the MOSFET structure. The calculated mobility has shown the oscillation with change in the Fermi level (the gate voltage), resulting in the transconductance oscillation. The oscillation originates from one-dimensional density of states (∝E−0.5).

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Mobility oscillation by one-dimensional quantum confinement in Si-nanowire metal-oxide-semiconductor field effect transistors

Effects of high-temperature (1400 °C–1600 °C) N2 annealing on the interface states of 4H- SiC/SiO2 and the channel mobility of 4H-SiC metal–oxide–semiconductor field-effect transistors (MOSFETs) were investigated. It is demonstrated that high-temperature N2 annealing is effective not only for the reduction of the interface state density near the conduction band edge but also for that near the valence band edge. N2 annealing improves channel mobility of both n- and p-channel MOSFETs as in the case of nitric oxide (NO) annealing. In particular, the field-effect mobility of the p-channel MOSFETs annealed in an N2 ambient was improved to 17 cm2/Vs, which is 30% higher than that of NO-annealed MOSFETs. The interface state density estimated from the subthreshold slopes in the MOSFETs is much higher than that extracted by the high–low method but is almost comparable to that estimated by the ${C}$ – $\psi _{\text {s}}$ method in both the cases of interface states near the conduction and the valence band edges. These results suggest that there exist fast states (>1 MHz) near the valence band edge, and these fast states affect the channel mobilities of p-channel SiC MOSFETs as in the case of n-channel MOSFETs.

Improvement of Both n- and p-Channel Mobilities in 4H-SiC MOSFETs by High-Temperature N₂ Annealing

We report that annealing in low-oxygen-partial-pressure (low-p$_{\rm O2}$) ambient is effective in reducing the interface state density (D$_{\rm IT}$) at a SiC (0001)/SiO$_{\rm 2}$ interface near the conduction band edge (E$_{\rm C}$) of SiC. The D$_{\rm IT}$ value at E$_{\rm C}$$-$0.2 eV estimated by a high (1 MHz)-low method is 6.2$\times$10$^{12}$ eV$^{-1}$cm$^{-2}$ in as-oxidized sample, which is reduced to 2.4${\times}$10$^{12}$ eV$^{-1}$cm$^{-2}$ by subsequent annealing in O$_{\rm 2}$ (0.001%) at 1500${}^\circ$C, without interface nitridation. Although annealing in pure Ar induces leakage current in the oxide, low-p$_{\rm O2}$ annealing (p$_{\rm O2}$ = 0.001 - 0.1 %) does not degrade the oxide dielectric property (breakdown field ~ 10.4 MVcm$^{-1}$).

Reduction of interface state density in SiC (0001) MOS structures by low-oxygen-partial-pressure annealing

We investigated electrical characteristics of nitric oxide (NO)-annealed silicon carbide (SiC) ( 0001 ), ( 11 2 ¯ 0 ), and ( 1 1 ¯ 00 ) metal-oxide-semiconductor field effect transistors (MOSFETs) with heavily doped p-bodies (NA = 1 × 1017–3 × 1018 cm−3). Regardless of crystal faces or off-direction, the channel mobility decreased for higher acceptor density. We evaluated the interface state density (Dit) very near the bottom edge of 2-dimensional density of states (2D-DOS) in the conduction band of SiC from the low-temperature subthreshold slope of the MOSFETs. When the acceptor density of the p-body of the MOSFET is increased, the energy levels of 2D-DOS increase due to a stronger quantum confinement effect. Accordingly, the carriers in the heavily doped channel are influenced by the interface states located at higher energy levels. In the SiC MOS structures, the Dit values significantly increase near the conduction band edge (EC). Thus, MOSFETs on heavily doped p-bodies are affected by the higher densi...

Interface properties of NO-annealed 4H-SiC (0001), ( 11 2 ¯ 0), and ( 1 1 ¯ 00) MOS structures with heavily doped p-bodies

The critical condition for expansion/contraction of single Shockley-type stacking faults (1SSFs) was experimentally estimated by monitoring the electroluminescence from 1SSFs in 4H-SiC PiN diodes with different p/n structures while varying the current density and the temperature. The “threshold current density” for expansion/contraction of 1SSF was determined by observing the 1SSF behavior, and it was converted to the “threshold excess carrier density” using the numerical calculation by device simulation. The threshold excess carrier density was almost independent of the diode structures though the threshold current densities were very different among the various diodes, which means that the 1SSF behavior does not depend on the current density but on the excess carrier density. The threshold excess carrier density at room temperature was estimated to be about 4 × 10 14 cm − 3, which agrees with the result calculated by a theoretical model previously proposed. In addition, the conduction type- and the doping concentration-dependences of the threshold excess carrier density were discussed.

Tsunenobu Kimoto

Papers

Mobility oscillation by one-dimensional quantum confinement in Si-nanowire metal-oxide-semiconductor field effect transistors

Improvement of Both n- and p-Channel Mobilities in 4H-SiC MOSFETs by High-Temperature N₂ Annealing

Reduction of interface state density in SiC (0001) MOS structures by low-oxygen-partial-pressure annealing

Interface properties of NO-annealed 4H-SiC (0001), ( 11 2 ¯ 0), and ( 1 1 ¯ 00) MOS structures with heavily doped p-bodies

Estimation of the critical condition for expansion/contraction of single Shockley stacking faults in 4H-SiC PiN diodes