RH. Jones et al. /Jounal of Nuclear Materials 307-311(2002)1057-1072 10 keV Si PKA Ct9 60 40 o Antisite Defects 0.001 0.01 Time( ps) Fig. 1. Number of interstitials and antisite defects produced in a 10 keV Si cascade as a function of time [10] 98 3C-SiC Net Displacements Fig. 3. MD simulation of primary damage state in SiC at 300K Si PKA Damage Energy(kev) due to a 10 keV Si PKA 8. The Si and c defects are dark and light gray, respectively, and the interstitials, antisite defects and Fig. 2. Net displacements and antisite defects produced as a vacancies are given by large, medium, and small spheres, unction of Si PKA damage energy [10 spectively number of C displacements is much larger than the (dpa)for irradiation with 550 keV Si* ions at 190 K[12 number of Si displacements, which is consistent with 14. The solid curve (Fig. 4) is based on the direct recent experimental observations [5]. Similar behavior is impact/defect-stimulated model for amorphization [15]. observed for C PKAs. Antisite defects are produced by where point defects, such as interstitials and antisite nearest-neighbor replacements during the collisional defects, stimulate the growth of amorphous nuclei (or phase and some random interstitial-vacancy recombi- defect clusters) produced directly in a displacement nation during the subsequent relaxation phase cascade. As the dose increases, cascade superposition MD simulations, as illustrated in Fig. 3, have also and defect-stimulated growth at crystalline-amorphous shown that Si PKAs generate only small interstitial interfaces become more probable. The relative ratio of clusters, with most defects being isolated single inter- direct- impact and defect-stimulated cross sections from stitials and vacancies distributed over a large region the model fit to the data for Si are consistent with those [8, 12, 13]. These predictions are in agreement with the derived from the MD simulations based on relative interpretation of the experimental results on disordering cluster distributions [121 behavior in SiC, as shown in Fig. 4, where the relative MD methods with 10 key si pkas have been em- order on the Si sublattice in Sic at the damage peak ployed to simulate cascade overlap, damage accumula shown as a function of dose in displacements per atom tion and amorphization processes in 3C-SiC. In thisnumber of C displacements is much larger than the number of Si displacements, which is consistent with recent experimental observations [5]. Similar behavior is observed for C PKAs. Antisite defects are produced by nearest-neighbor replacements during the collisional phase and some random interstitial-vacancy recombi￾nation during the subsequent relaxation phase. MD simulations, as illustrated in Fig. 3, have also shown that Si PKAs generate only small interstitial clusters, with most defects being isolated single inter￾stitials and vacancies distributed over a large region [8,12,13]. These predictions are in agreement with the interpretation of the experimental results on disordering behavior in SiC, as shown in Fig. 4, where the relative disorder on the Si sublattice in SiC at the damage peak is shown as a function of dose in displacements per atom (dpa) for irradiation with 550 keV Siþ ions at 190 K [12– 14]. The solid curve (Fig. 4) is based on the direct￾impact/defect-stimulated model for amorphization [15], where point defects, such as interstitials and antisite defects, stimulate the growth of amorphous nuclei (or defect clusters) produced directly in a displacement cascade. As the dose increases, cascade superposition and defect-stimulated growth at crystalline-amorphous interfaces become more probable. The relative ratio of direct-impact and defect-stimulated cross sections from the model fit to the data for Si are consistent with those derived from the MD simulations based on relative cluster distributions [12]. MD methods with 10 keV Si PKAs have been em￾ployed to simulate cascade overlap, damage accumula￾tion and amorphization processes in 3C–SiC. In this Fig. 3. MD simulation of primary damage state in SiC at 300 K due to a 10 keV Si PKA [8]. The Si and C defects are dark and light gray, respectively, and the interstitials, antisite defects and vacancies are given by large, medium, and small spheres, re￾spectively. Fig. 1. Number of interstitials and antisite defects produced in a 10 keV Si cascade as a function of time [10]. Fig. 2. Net displacements and antisite defects produced as a function of Si PKA damage energy [10]. R.H. Jones et al. / Journal of Nuclear Materials 307–311 (2002) 1057–1072 1061