Development of the ReaxFF Reactive Force Field for Cu/Si Systems with Application to Copper Cluster Formation during Cu Diffusion Inside Silicon
Development of the ReaxFF Reactive Force Field for Cu/Si Systems with Application to Copper Cluster Formation during Cu Diffusion Inside Silicon
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DOI：
10.1021/acs.jpcc.1c04178
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发表时间：
2021-08
期刊：
影响因子：
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通讯作者：
Kamyar Akbari Roshan;Mahdi Khajeh Talkhoncheh;J. Mueller;W. Goddard;A. V. van Duin
中科院分区：
文献类型：
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作者：
Kamyar Akbari Roshan;Mahdi Khajeh Talkhoncheh;J. Mueller;W. Goddard;A. V. van Duin
硅等固态材料中的过渡金属杂质，如镍、铜和铁，对集成电路和太阳能电池的电气性能有重大影响。为了研究大块硅中铜杂质对材料电性能的影响，需要了解硅晶格中铜原子的构型空间。在这项工作中，我们开发了一个ReaxFF反应力场，并使用它对多达762个原子的模型进行分子动力学模拟，通过检查铜在硅中的扩散行为，研究大块硅中铜原子的个体和晶体簇的各种构型。ReaxFF Cu/Si参数集是通过训练密度泛函理论（DFT）数据开发的，包括单个Cu原子在硅晶格内运动的能量势垒。我们发现铜原子的扩散与温度有关。此外，我们还表明，当温度高于500 K时，单个铜原子开始在大块硅内部形成团簇。我们的模拟结果提供了对温度和铜浓度对硅晶格内铜簇形成的影响的全面理解。最后，得到了Cu/Si化合物在单轴拉伸载荷下的应力应变关系。我们的结果表明，弹性模量随着cu杂质浓度的增加而降低。在应力应变测试中，我们观察到Si的自发微裂纹，这是由于在Si表面附近形成了一个小的Cu簇。
Transition-metal impurities such as nickel, copper, and iron in solid-state materials like silicon have a significant impact on the electrical performance of integrated circuits and solar cells. To study the impact of copper impurities inside bulk silicon on the electrical properties of the material, one needs to understand the configurational space of copper atoms incorporated inside the silicon lattice. In this work, we developed a ReaxFF reactive force field and used it to perform molecular dynamics simulations on models with up to 762 atoms to study the various configurations of individual and crystalline clusters of copper atoms inside bulk silicon by examining copper’s diffusional behavior in silicon. The ReaxFF Cu/Si parameter set was developed by training against density functional theory (DFT) data, including the energy barrier for an individual Cu atom traveling inside a silicon lattice. We found that the diffusion of copper atoms is dependent on temperature. Moreover, we show that individual copper atoms start to form clusters inside bulk silicon at temperatures above 500 K. Our simulation results provide a comprehensive understanding of the effects of temperature and copper concentration on the formation of copper clusters inside a silicon lattice. Finally, the stress–strain relationship of Cu/Si compounds under uniaxial tensile loading has been obtained. Our results indicate a decrease in the elastic modulus with increasing Cu-impurity concentration. We observe spontaneous microcracking of the Si during the stress–strain tests as a consequence of the formation of a small Cu cluster adjacent to the Si surface.