Models for phase-change of Ge2Sb2Te5 in optical and electrical memory devices
Models for phase-change of Ge2Sb2Te5 in optical and electrical memory devices
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DOI：
10.1063/1.1633984
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发表时间：
2004-01-15
影响因子：
3.2
通讯作者：
Wright, CD
中科院分区：
文献类型：
--
作者：
Senkader, S;Wright, CD
我们研究了三种不同的建模方法来模拟光学相变存储器和最近的电相变存储器中 Ge2Sb2Te5 的结晶行为。第一个模型基于 Johnson-Mehl-Avrami-Kolmogorov (JMAK) 形式主义，用于计算等温退火期间结晶材料的分数。在文献中，该模型被广泛使用，但不同研究者报告的模型参数差异很大。我们已经证明，这些差异可归因于 JMAK 方法的不当使用。为了克服 JMAK 理论施加的限制，人们提出了基于经典成核理论的概括。理论所需的材料参数，例如 Ge2Sb2Te5 的粘度、扩散率和熔化焓，已从已发表的实验中推导出来。然而，材料参数的不确定性与经典成核理论使用的近似表达式相结合，使我们提出了基于速率方程的综合模型。尽管更复杂，但这种建模方法产生了更有利和可靠的结果。我们讨论了不同的模拟实验比较来说明模型的功能。 (C) 2004 年美国物理研究所。
We investigated three different modeling approaches to simulate the crystallization behavior of Ge2Sb2Te5 in optical and, very recently, electrical phase-change memories. The first of these models is based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) formalism to calculate the fraction of crystallized material during isothermal anneals. In the literature, this model is widely used, but parameters of the model reported by different investigators vary considerably. We have shown that these discrepancies can be attributed to the inappropriate use of the JMAK approach. In order to overcome the restrictions imposed by JMAK theory, generalizations based on classical nucleation theory have been suggested. Material parameters required by the theory, such as viscosity, diffusivity, and fusion enthalpy of Ge2Sb2Te5, have been deduced from published experiments. Uncertainty in the material parameters in combination with approximate expressions used by the classical nucleation theory, however, lead us to suggest a comprehensive model based on rate equations. Although it is more complicated, this modeling approach has yielded more favorable and reliable results. We have discussed different simulation-experiment comparisons to illustrate the capabilities of the model. (C) 2004 American Institute of Physics.