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

The threshold displacement energy (TDE) for both Si and C atoms in SIC at 3 00 K has been determined by means of molecular dynamics (MD) simulation alo ng four crystallographic directions: [0 0 1], [1 1 0], [1 1 1] and [(1) ove r bar (1) over bar (1) over bar]. The existence of recombination barriers, which allow the formation of metastable defects even below the threshold, h as been observed. Displacement cascades produced by both C and Si recoils o f 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 w ith the analysis of a damage accumulation at 1300 K, reveals that the two s ublattices 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 pr events the study of defect evolution within the scope of MD. (C) 2000 Elsev ier Science B.V. All rights reserved.