Configurational entropy significantly influences point defect thermodynamics and diffusion in crystalline silicon
Configurational entropy significantly influences point defect thermodynamics and diffusion in crystalline silicon
复制标题
构型熵显着影响晶体硅中的点缺陷热力学和扩散
DOI：
10.1103/physrevmaterials.6.064603
复制
发表时间：
2022
影响因子：
3.4
通讯作者：
Talid Sinno
中科院分区：
文献类型：
--
作者：
Jinping Luo;Chenyang Zhou;Yunjie Cheng;Qihang Li;Lijun Liu;Jack F. Douglas;Talid Sinno
It has long been suggested that the familiar intrinsic point defects (vacancies and self-interstitials) encountered in crystals at low temperatures ($T$) transform into extended domains characterized by a missing or excess atom compared with the same-sized region in the perfect crystal so that such extended defects may be viewed as dropletlike regions of enhanced or diminished density. However, the implications of such a transformation, or whether it even occurs in crystalline Si, remain uncertain. To address this fundamental problem, we consider a comprehensive thermodynamic analysis of the thermodynamics of vacancy and self-interstitial formation over a broad $T$ range based on thermodynamic integration with a focus on entropic contributions. In cooled liquids, it is well known that the form of the intermolecular potential can greatly influence the configurational entropy ${S}_{c}$, and correspondingly, we analyze several empirical Si potentials to determine how the potential influences both the $T$ dependence of ${S}_{c}$ and the enthalpy and entropy of defect formation. We indeed find that the ${S}_{c}$ associated with point defects increases significantly upon heating, consistent with the existence of extended defects. Moreover, each type of defect species gives a significantly different contribution to ${S}_{c}$ at elevated $T$ and to a qualitive difference in the $T$ dependence of the entropy of defect formation in the extended defect regime. We discuss some potential consequences of these thermodynamic changes of defect formation on the $T$ dependence of diffusion in heated crystals.
