Torres Pol, Mohammed Amr, Torelló Àlvar, Bafaluy Javier, Camacho Juan, Cartoixà Xavier, Shakouri Ali, Alvarez F Xavier
Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain.
Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
Phys Chem Chem Phys. 2018 Mar 7;20(10):6805-6810. doi: 10.1039/c7cp07738f.
Conventional models for predicting thermal conductivity of alloys usually assume a pure kinetic regime as alloy scattering dominates normal processes. However, some discrepancies between these models and experiments at very small alloy concentrations have been reported. In this work, we use the full first principles kinetic collective model (KCM) to calculate the thermal conductivity of SiGe and InGaAs alloys. The calculated thermal conductivities match well with the experimental data for all alloy concentrations. The model shows that the collective contribution must be taken into account at very low impurity concentrations. For higher concentrations, the collective contribution is suppressed, but normal collisions have the effect of significantly reducing the kinetic contribution. The study thus shows the importance of the proper inclusion of normal processes even for alloys for accurate modeling of thermal transport. Furthermore, the phonon spectral distribution of the thermal conductivity is studied in the framework of KCM, providing insights to interpret the superdiffusive regime introduced in the truncated Lévy flight framework.
预测合金热导率的传统模型通常假定为纯动力学机制，因为合金散射主导了正常过程。然而，已有报道称在合金浓度非常低时，这些模型与实验之间存在一些差异。在这项工作中，我们使用全第一性原理动力学集体模型（KCM）来计算SiGe和InGaAs合金的热导率。计算得到的热导率与所有合金浓度下的实验数据都匹配良好。该模型表明，在极低杂质浓度下必须考虑集体贡献。对于较高浓度，集体贡献受到抑制，但正常碰撞会显著降低动力学贡献。因此，该研究表明，即使对于合金，正确纳入正常过程对于准确模拟热输运也很重要。此外，在KCM框架内研究了热导率的声子谱分布，为解释截断的列维飞行框架中引入的超扩散机制提供了见解。
