Molecular Dynamics Study Of SiC Cascading Collisions

Because silicon carbide(SiC)has a series of similar crystal structure of the homogeneous polytype body makes silicon carbide has the characteristics of homogeneous polycrystal.so it has many special excellent performances,is widely used in semiconductor,high temperature applications,ultraviolet light detection,heating element,astronomy,clutch and other fields.In the field of nuclear science,SiC can be used as the cladding material of nuclear fuel and is also one of the candidate materials for the first wall material of fusion reactor.The use of SiC in electronic equipment and neutron irradiation environment has aroused great scientific interest.When exposed to high-energy neutrons,the microstructure of SiC will change,which will affect other properties of the material.The study of the details of this process is of positive significance not only for regulating the structure of materials,but also for predicting the properties of materials.We use molecular dynamics modeling of atomic displacement cascading to describe the properties of primary radiation damage in SiC.Three common SiC configurations,3C-SiC,4H-SiC and 6H-SiC,were selected as the research objects.Molecular dynamics simulation of the above SiC configurations under different PKA energies and different ambient temperatures was carried out by using ATK simulation software.The simulation process of 4H-SiC cascading collision is compared with the results of relevant literatures in detail,and the results show that our calculation model has good accuracy.It is found that C atomic defects are mainly generated in the cascade collision process of SiC.When the PKA energy is lower than 8 keV,the number of CSI anti-position defects produced by 6H-SiC is not affected by the PKA energy.When the energy is higher than 10 keV,the number of CSI anti-position defects is significantly increased.This is determined by the more complex and stable stacking mode of 6H-SiC.There is no regular relationship between the antiposition defects of 3C-SiC and the change of PKA energy,while the number of antiposition defects of 4H-SiC is positively correlated with the PKA energy.When the temperature is lower than 1200 K,there is no obvious effect on the cascading collision process of SiC.When the temperature is higher than 1500 K,it mainly promotes the formation of defects,and the strength of this effect decreases first and then increases with the increase of temperature.The increase of PKA energy has a great influence on the generation rate of defects,in which the generation rate of 3C-SiC defects increases first and then decreases with the increase of PKA energy,and the maximum defect generation rate occurs at 4 keV.The defect generation rate of 4H-SiC is maintained at a relatively stable level.However,there is no regular change in 6H-SiC,and the defect generation is the fastest at 8 keV and the lowest at 6 keV.At low energy PKA,3C-SiC produces the most stable defects,while at high energy PKA,6H-SiC produces the most stable defects.At the same PKA energy,3C-SiC produces the most C vacancy and Si vacancy atoms,while 6H-SiC produces the most C vacancy atoms and Si vacancy atoms.