Ab Initio Computer Simulation of the Early Stages of Crystallization: Application to Ge2Sb2Te5 Phase-Change Materials
Ab Initio Computer Simulation of the Early Stages of Crystallization: Application to Ge2Sb2Te5 Phase-Change Materials
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DOI：
10.1103/physrevlett.107.145702
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发表时间：
2011-09-27
影响因子：
8.6
通讯作者：
Elliott, S. R.
中科院分区：
文献类型：
--
作者：
Lee, T. H.;Elliott, S. R.
凭借相变存储材料的超短相变时间，例如例如，Ge2Sb2Te5，我们使用从头算分子动力学模拟成功地重现了这种材料的早期结晶阶段。发现结晶起始时间的随机分布，正如经典成核理论中通常假设的那样。估计临界晶核由 5-10 个 (Ge;Sb)(4)Te-4 立方体组成。非晶 Ge2Sb2Te5 中晶体团簇的模拟生长速率与外推实验测量结果一致。非晶相中有序平面结构的形成对于降低晶簇与非晶相之间的界面能起着至关重要的作用，这解释了为什么Ge-Sb-Te材料表现出超快结晶。
By virtue of the ultrashort phase-transition time of phase-change memory materials, e. g., Ge2Sb2Te5, we successfully reproduce the early stages of crystallization in such a material using ab initio molecular-dynamics simulations. A stochastic distribution in the crystallization onset time is found, as generally assumed in classical nucleation theory. The critical crystal nucleus is estimated to comprise 5-10 (Ge; Sb)(4)Te-4 cubes. Simulated growth rates of crystalline clusters in amorphous Ge2Sb2Te5 are consistent with extrapolated experimental measurements. The formation of ordered planar structures in the amorphous phase plays a critical role in lowering the interfacial energy between crystalline clusters and the amorphous phase, which explains why Ge-Sb-Te materials exhibit ultrafast crystallization.