Evaluation and Reduction of Epitaxial Wafer Defects Resulting from Carbon-Inclusion Defects in 4H-SiC Substrate

In this study, we investigated the epitaxial surface defects resulting from the carbon-inclusion defects in 4H-SiC substrate. Most carbon-inclusion defects developed into one of three types of epitaxial surface defects under normal epitaxial growth conditions. Among them, we found a regular hexagonal pit by high-resolution microscopy, which we regarded as a large-pit defect, and which had an adverse impact on the reverse electrical characteristics of Schottky barrier diodes. Conversion of a carbon-inclusion defect to a large-pit defect or a triangular defect could be reduced by reducing the C/Si ratio.

Influence of Carbon Inclusion on the Electrochemical Performances for Si Using as the Lithium-Ion Battery Anode

Si/C composite was prepared using different procedures and different C sources in this work. According to the electrochemical performances, it was found that the discharge capacity for Si/C composite (SC1) by the electrostatic spinning procedure using polyvinylpyrrolidone as the C source was 2200mAh/g. In contrast, the cell with the pure Si particle exhibited an initial discharge capacity of only 13mAh/g. Moreover, after 30 cycles, SC1 sample had the higher capacities and the better capacity retention performances than other samples because of its lower charge transfer resistance. The inclusion of carbon not only worked as a stable electric conductive pathway but also buffer the volume expansion of the silicon during the process of charging and discharging.

Carbon Substitution on N24Cages: Crossover between Triangular and Hexagonal Structures

Complex forms of nitrogen are of interest for their potential as high-energy materials, but many all-nitrogen systems lack the stability for practical high-energy applications. Inclusion of carbon atoms in an otherwise all-nitrogen structure can increase stability. Nitrogen cages are known for energetically preferring cylindrical structures with triangular endcaps, but carbon cages prefer the pentagon-hexagon structure of the fullerenes. Previous calculations on N22C2have shown that carbon inclusion narrows the gap between triangular and fullerene-like structures. In the current study, three isomers of N24are used as frameworks for carbon substitution. Theoretical calculations are carried out on isomers of N20C4, N18C6, and N16C8, with the goal of determining what level of carbon substitution causes the carbon fullerene-like structures to become energetically preferred.

Impedance Changes and Carbon Stability during the Heat Treatment of Si3N4–Carbon Composites

Electrical properties of the insulator silicon nitride ceramics may be improved by addition of electrical conductive parts. The conductive carbon parts were mixed with the base ceramic matrix to form a percolation network. Electrical current can flow through the ceramic by using the connected carbon channels. In air atmosphere however, the carbon can oxidize and burn out. Heat treatments were performed to observe the carbon degradation in composites in atmosphere. As resulted, the carbon exhaust started at 400°C from surface and finished above 750°C. Electrical measurements showed the conductor-insulator transformation. Thermo-gravimetric measurements suggested that some carbon inclusion still remained in isolated closed porosities.