Silicon carbide (SiC) is regarded as the important structural material used in nuclear power, due to its good physical and chemical properties, such as high thermal conductivity, low neutron capture, high melting point, and low corrosion rate. Stacking faults are important for improving radiation resistance of SiC. A new method has been developed at CIRP to fabricate stacking faults by recrystallization of amorphous SiC, which was formed by Si implantation at room temperature.
Increase in defect recovery and enhancing desorption of gas in SiC are necessary for improving the structural stability. It has been found that radiation-resistance increases in nano-engineered SiC (NESiC) with a high density of stacking faults. First-principles calculations confirmed the migration barrier for Si interstitials decreases near the stacking faults, leading to the increase in defect annihilation in NE-SiC. Nanostructured SiC can improve the radiation resistance. Stacking faults can be fabricated by low-pressure chemical vapor deposition (CVD).
CIRP studied recrystallization of amorphous SiC with three different types and found:
- A high density of stacking faults were formed by recrystallization of amorphous SiC. The space distance of stacking faults is less than 1 nm, which is smaller than the value obtained by CVD.
- The length of stacking faults depends on the thickness of amorphous layer, not like CVD that usually produce tens to several hundred nanometers.
- Defects migrate toward the sample surface rapidly when the habit plane of stacking faults is perpendicular to the irradiation surface.
XTEM bright-field ((a), (c), (e)) and dark-field ((b), (d), (f)) images showing extended defects in the damaged layer of
three kinds of grains. Arrow indicates the normal direction of the sample surface
Radiation-resistant SiC can be fabricated by recrystallization of ion implantation-induced amorphous SiC. That will provide reference for designing radiation resistant SiC in the future.
Contact: official@cirp.org.cn