Atomic-scale simulation of 50 keV Si displacement cascades in β-SiC
Atomic-scale simulation of 50 keV Si displacement cascades in β-SiC
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DOI：
10.1103/physrevb.63.054101
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发表时间：
2001-02-01
影响因子：
3.7
通讯作者：
Weber, WJ
中科院分区：
文献类型：
--
作者：
Gao, F;Weber, WJ
采用修正的特尔索夫势的分子动力学(MD)方法模拟了高能(50keV)的β-碳化硅的位移级联。结果表明，级联寿命很短，比金属的寿命短10倍，残存缺陷主要由C间隙和空位组成，这与10keV级联的情况类似。在两个亚晶格上都产生了反位缺陷。尽管级联末端残留的反位缺陷总数比Frenkel对的少，但Si反位的数量大于Si间隙的数量。大多数残存缺陷是单个间隙和空位，只有19%的间隙人口以簇状形式存在。间隙团簇的尺寸很小，在所有考虑的级联中，发现的最大的团簇只包含四个间隙原子，这与金属中的MD模拟得到的行为有很大的不同。观察到，从级联的碰撞阶段到它们的最终排列，所有的团簇都是由淬火机制直接产生的。初始Si反冲平均行进约65 nm，形成多个子级联，并在级联几何结构中形成分散排列。这些结果表明，在硅级联寿命过程中，即使存在高能反冲，碳化硅中的级联或直接碰撞非晶化的概率也不高，这与以前的实验和分子动力学观测结果一致。
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 interstitials and vacancies, which is similar to behavior for 10 keV cascades in SiC. Antisite defects are generated on both sublattices. Although the total number of antisite defects remaining at the end of the cascade is smaller than that of Frenkel pairs, the number of Si antisites is larger than the number of Si interstitials. Most surviving defects are single interstitials and vacancies, and only 19% of the interstitial population is contained in clusters. The size of the interstitial clusters is small, and the largest cluster found, among all the cascades considered, contained only four interstitial atoms, which is significantly different behavior than obtained by MD simulations in metals. It is observed that all clusters are created by a quenched-in mechanism directly from the collisional phase of the cascade to their final arrangements. The initial Si recoil traveled about 65 nm on average, generating multiple subcascades and forming a dispersed arrangement in the cascade geometry. These results suggest that in-cascade or direct-impact amorphization in SiC does not occur with any high degree of probability during the cascade lifetime of Si cascades, even with high-energy recoils, consistent with previous experimental and MD observations.