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

Power semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide-bandgap semiconductor suitable for high-voltage and low-loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium-voltage (600?1700 V) SiC Schottky barrier diodes (SBDs) and power metal?oxide?semiconductor field-effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.

https://iopscience.iop.org/article/10.7567/JJAP.54.040103/pdf

Material science and device physics in SiC technology for high-voltage power devices

With low energy electron irradiation in the 80–250keV range, we were able to create only those intrinsic defects related to the initial displacements of carbon atoms in the silicon carbide lattice. Radiation induced majority and minority carrier traps were analyzed using capacitance transient techniques. Four electron traps (EH1, Z1∕Z2, EH3, and EH7) and one hole trap (HS2) were detected in the measured temperature range. Their concentrations show linear increase with the irradiation dose, indicating that no divacancies or di-interstitials are generated. None of the observed defects was found to be an intrinsic defect–impurity complex. The energy dependence of the defect introduction rates and annealing behavior are presented and possible microscopic models for the defects are discussed. No further defects were detected for electron energies above the previously assigned threshold for the displacement of the silicon atom at 250keV.

Deep levels created by low energy electron irradiation in 4H-SiC

The present state of SiC power Schottky and PiN diodes are presented in this paper. The design, fabrication, and characterization of a 130 A Schottky diode, 4.9 kV Schottky diode, and an 8.6 kV 4H-SiC PiN diode, which are considered to be significant milestones in the development of high power SiC diodes, are described in detail. Design guidelines and practical issues for the realization of high-power SiC Schottky and PiN diodes are also presented. Experimental results on edge termination techniques applied to newly developed, extremely thick (e.g., 85 and 100 /spl mu/m) 4H-SiC epitaxial layers show promising results. Switching and high-temperature measurements prove that SiC power diodes offer extremely low loss alternatives to conventional technologies and show the promise of demonstrating efficient power circuits. At sufficiently high on-state current densities, the on-state voltage drop of Schottky and PiN diodes have been shown to be comparable to those offered by conventional technologies.

SiC power Schottky and PiN diodes

SiC materials are currently metamorphosing from research and development into a market driven manufacturing product. SiC substrates are currently used as the base for a large fraction of the world production of green, blue, and ultraviolet light-emitting diodes (LEDs). Emerging markets for SiC homoepitaxy include high-power switching devices and microwave devices for S and X band. Applications for heteroepitaxial GaN-based structures on SiC substrates include LEDs and microwave devices. In this paper we review the properties of SiC, assess the current status of substrate and epitaxial growth, and outline our expectations for SiC in the future.

SiC materials-progress, status, and potential roadblocks

Characterization of two negative-U centers in 4H SiC has been performed using various capacitance transient techniques. Each center gives rise to one acceptor level (-/0) and one donor level (0/+), where the electron ionization energy of the acceptor level is larger than that of the donor level. The two-electron emissions from the two acceptor levels give rise to the previously reported deep level transient spectroscopy peak associated with the so-called ${Z}_{1}$ center. Direct evidence for the inverted ordering and temperature dependence studies of the electron-capture cross sections of the acceptor levels will be presented.

Negative- U centers in 4 H silicon carbide

Two high temperature CVD techniques, respectively optimised for epitaxial and crystal growth, are presented. A chimney reactor has been developed for fast epitaxy, carried out at 1700‐1900°C, with growth rates ranging from 10 to 25 m mh 1 , and a material quality close to conventional CVD processes. The growth of 4H-SiC epilayers with low n-type doping (10 14 ‐10 15 cm 3 ) and carrier lifetimes up to 0.4 ms is described, while the feasibility of high voltage Schottky rectifiers (1.8 kV) is demonstrated. On the other side, developments of the stagnant flow HTCVD process, where growth is carried out at 2000‐2300°C, are shown to enable growth rates ranging from 0.3 up to 0.8 mm h 1 . The main characteristics of HTCVD grown SiC crystals (up to nearly 7 mm thick) are described. © 1999 Elsevier Science S.A. All rights reserved.

High temperature CVD growth of SiC

Epitaxial growth of SiC in a chimney CVD reactor

The epitaxial growth of SiC is investigated in a CVD process based on a vertical hot-wall, or "chimney", reactor geometry. Carried out at increased temperatures (1650 to 1850 degreesC) and concentr ...

Jie Zhang

Papers

Negative- U centers in 4 H silicon carbide

High temperature CVD growth of SiC

Epitaxial growth of SiC in a chimney CVD reactor

Fast SiC Epitaxial Growth in a Chimney CVD Reactor and HTCVD Crystal Growth Developments

Nitrogen incorporation during 4H-SiC epitaxy in a chimney CVD reactor