A high density of growth twins is commonly observed within individual Si nanowires as well as Si nanofibers in rapidly solidified Al-Si eutectic. Using atomistic simulations and topological model for pure Si, we reveal two types of twinning dislocations, Shockley partial bp=16〈11‾2〉 and synchroshear dislocation bt=13〈112¯〉, and confirmed that synchroshear dislocation is more mobile than Shockley partial although synchroshear dislocation has larger magnitude Burgers vector. Both synchroshear dislocations and Shockley partials have higher kinetic barriers for glide on glide-set plane in perfect Si crystal than on CTB in twinned crystal. Regarding slip transmission across CTBs, a mixed full dislocation is blocked by the CTB, while slip transmission does occur via cross-slip mechanism when a screw full dislocation interacts with CTBs. When an edge synchroshear dislocation interacts with an CTB, slip transmission takes place via emitting a screw full dislocation nucleates on the SS while an edge Shockley partial is left on the CTB. Most surprising, CTB-assisted full dislocations gliding has been observed in simulating dislocation loop contraction. This is attributed to two changes in dislocation behavior. Full edge dislocation that is sessile on shuffle-set in perfect crystal becomes significantly glissile on CTB due to a wider core. For full screw dislocation, cross-slip and core transition are suppressed and planar glide mobility on CTB is enhanced as compared to a full screw dislocation on shuffle-set in perfect crystals. The implication of these simulation results on recent experimental observations of room temperature dislocation glide in twinned Si nanofibers are discussed.

中文翻译：

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孪晶界对硅位错特性和运动的影响


在单个 Si 纳米线以及快速凝固的 Al-Si 共晶中的 Si 纳米纤维中通常观察到高密度的生长孪晶。使用纯硅的原子模拟和拓扑模型，我们揭示了两种类型的孪晶位错，Shockley 部分 bp=16〈11 ̅2〉 和同步剪切位错 bt=13〈112 ̄〉，并证实了同步剪切位错比 Shockley 部分位错更具移动性，尽管同步剪切位错具有更大的 Burgers 向量量级。同步剪切位错和 Shockley 部分位错在完美 Si 晶体的滑行平面上比在孪晶中的 CTB 上具有更高的滑行动力学障碍。关于跨 CTB 的滑移传递，混合全位错被 CTB 阻断，而当螺钉全位错与 CTB 相互作用时，滑移传递确实通过交叉滑移机制发生。当边缘同步剪切位错与 CTB 相互作用时，滑移传输是通过在 SS 上发射一个螺钉完全位错成核而发生在 CTB 上，而边缘 Shockley 部分留在 CTB 上。最令人惊讶的是，在模拟位错袢收缩时观察到 CTB 辅助的完全位错滑动。这归因于位错行为的两种变化。由于纤芯较宽，在完美晶体中随机设置的全边缘位错在 CTB 上变得明显眩光。对于全螺钉位错，与完美晶体中随机设置的全螺钉位错相比，抑制了交叉滑移和核心过渡，增强了 CTB 上的平面滑移移动性。讨论了这些模拟结果对最近对孪晶硅纳米纤维中室温位错滑动的实验观察的影响。