Analysis of displacement cascades and threshold displacement energies in β-sic

Abstract

The threshold displacement energy (TDE) for both Si and C atoms in SiC at 300 K has been determined by means of molecular dynamics (MD) simulation along four crystallographic directions: [0 0 1], [1 1 0], [1 1 1] and [ 1 ̄ 1 ̄ 1 ̄ ] . The existence of recombination barriers, which allow the formation of metastable defects even below the threshold, has been observed. Displacement cascades produced by both C and Si recoils of energies spanning from 0.5 keV up to, respectively, 5 and 8 keV have also been simulated with MD, both at 300 and 1300 K. Their analysis, together with the analysis of a damage accumulation at 1300 K, reveals that the two sublattices exhibit opposite responses to irradiation: whereas only a little damage is produced on the ‘ductile’ Si sublattice, many defects accumulate on the much more ‘fragile’ C sublattice. The low defect mobility in SiC prevents the study of defect evolution within the scope of MD.