Molecular dynamics (MD) methods with a modified Tersoff potential have been
used to simulate high-energy (50 keV) displacement cascades in beta -SiC.
The results show that the cascade lifetime is very short, 10 times shorter
than that in metals, and the surviving defects are dominated by C interstit
ials and vacancies, which is similar to behavior for 10 keV cascades in SiC
. Antisite defects are generated on both sublattices. Although the total nu
mber of antisite defects remaining at the end of the cascade is smaller tha
n that of Frenkel pairs, the number of Si antisites is larger than the numb
er of Si interstitials. Most surviving defects are single interstitials and
vacancies, and only 19% of the interstitial population is contained in clu
sters. The size of the interstitial clusters is small, and the largest clus
ter found, among all the cascades considered, contained only four interstit
ial atoms, which is significantly different behavior than obtained by MD si
mulations in metals. It is observed that all clusters are created by a quen
ched-in mechanism directly from the collisional phase of the cascade to the
ir final arrangements. The initial Si recoil traveled about 65 nm on averag
e, generating multiple subcascades and forming a dispersed arrangement in t
he cascade geometry. These results suggest that in-cascade or direct-impact
amorphization in SiC does not occur with any high degree of probability du
ring the cascade lifetime of Si cascades, even with high-energy recoils, co
nsistent with previous experimental and MD observations.