Defect production, multiple ion-solid interactions and amorphization in SiC

Recent progress in the atomic-scale simulations of fundamental damage production processes in SiC is reviewed, which includes the displacement threshold energy surface, the primary damage state and statistics of defect production, multiple ion-solid collision events and structural evolution in SiC. The threshold energy surface, E-d, appears to be highly anisotropic, and the results of molecular dynamics (MD) simulations, in conjunction with experimental studies, suggest that Ed values of 20 eV for C and 35 eV for Si should be used in Kinchin-Pease calculations. The Si displacement cascades with energies up to 50 keV show that the surviving defects are dominated by C interstitials and vacancies, consistent with experimental observations. The defect production efficiency decreases with increasing recoil energy, but the number and size of clusters or complex domains formed at the end of cascades are very small, independent of cascade energy. A large number of 10 keV displacement cascades were randomly generated in a model crystal to simulate multiple ion-solid interaction and damage accumulation. The coalescence of clusters represents an important mechanism leading to the complete amorphization of SiC, and the relative disorder and swelling behavior show an excellent agreement with experimental observations. HRTEM images simulated from the MD cell reveal the microstructural evolution of multiple ion-solid collision events, and provide atomic-level interpretations of experimentally observed features in SiC. (C) 2002 Elsevier Science B.V. All rights reserved.