SiC polytypes have been studied for decades, both experimentally and with atomistic simulations, yet no consensus has been reached on the factors that determine their stability and growth. Proposed governing factors are temperature-dependent differences in the bulk energy, biaxial strain induced through point defects, and surface properties. In this work, we investigate the thermodynamic stability of the 3C, 2H, 4H, and 6H polytypes with density functional theory (DFT) calculations. The small differences of the bulk energies between the polytypes can lead to intricate changes in their energetic ordering depending on the computational method. Therefore, we employ and compare various DFT-codes: VASP, CP2K, and FHI-aims; exchange-correlation functionals: LDA, PBE, PBEsol, PW91, HSE06, SCAN, and RTPSS; and nine different van der Waals (vdW) corrections. At $T=0$~K, 4H-SiC is marginally more stable than 3C-SiC, and the stability further increases with temperature by including entropic effects from lattice vibrations. Neither the most advanced vdW corrections nor strain on the lattice have a significant effect on the relative polytype stability. We further investigate the energies of the (0001) polytype surfaces that are commonly exposed during epitaxial growth. For Si-terminated surfaces, we find 3C-SiC to be significantly more stable than 4H-SiC. We conclude that the difference in surface energy is likely the driving force for 3C-nucleation, whereas the difference in the bulk thermodynamic stability slightly favors the 4H and 6H polytypes. In order to describe the polytype stability during crystal growth correctly, it is thus crucial to take into account both of these effects.
Interfacial thermal transport in Si/SiC and SiC/diamond heterostructures: effects of amorphous interlayers and SiC polytypes
K. N. Toosi University of Technology（K.N.托辛理工大学）；Institute for Research in Fundamental Sciences（基础科学研究所）；Imam Khomeini International University（伊玛目霍梅尼国际大学）
The (3$\times$3)-SiC-($\bar{1}\bar{1}\bar{1}$) Reconstruction: Atomic Structure of the Graphene Precursor Surface from a Large-Scale First-Principles Structure Search
碳化硅（SiC）是用于大规模、高质量外延石墨烯的生长和操作的优良衬底。在碳面（（$\bar{1}\bar{1}\bar{1}$）或$(000\bar{1}$）面，取决于多型体）上，石墨烯生长的开始与几种竞争表面相的形成交织在一起，其中（3 $\times$ 3）前体相被怀疑阻碍石墨烯的受控、近平衡生长的开始。尽管经过了二十多年的研究，这个阶段的精确原子结构仍然不清楚。基于包含范德华效应的密度泛函理论，从{ \it ab initio}随机结构搜索出发，提出了（3 $\times$ 3）-SiC-（$\bar{1}\bar{1}\bar{1}$）重构的新模型.该结构由一个简单的图案的五个硅吸附原子在桥接和顶部的位置上的底层，C-终止的衬底层，留下一个C原子每（3 $\times$ 3）单电池形式上不饱和。模拟的扫描隧道显微镜（STM）的图像与先前报道的实验STM图像非常一致。
Elastic properties of cubic silicon carbide with Si vacancies
Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC)（马德里材料科学研究所，西班牙国家科学研究委员会）；CNR-IOM Democritos National Simulation Center, Istituto Officina dei Materiali（意大利国家研究委员会材料研究所德谟克利特国家模拟中心）
Molecular dynamics simulation study of mechanical properties of 3C-SiC with extended defects
V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院 V. 拉什卡拉里夫半导体物理研究所）；Educational Scientific Institute of High Technologies, Taras Shevchenko National University of Kyiv（基辅塔拉斯舍甫琴科国立大学高等技术教育科学研究所）；National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”（乌克兰国立技术大学“伊戈尔·西科尔斯基基辅理工学院”）
Design rules for the thermal and elastic properties of rare-earth disilicates
稀土硅酸盐是目前用作燃气涡轮发动机热段部件的SiC基陶瓷基复合材料的环境屏障涂层的标准材料。将设计空间扩展到所有可用的稀土元素以便于优化功能需要理解$RE_2$ Si $_2$ O $_7$性质的系统趋势。在这项工作中，我们结合第一性原理计算与实验测量的杨氏模量，热膨胀系数，和热导率的范围内不同的$RE_2$硅$_2$ O $_7$组合物和阶段。在这些性能中观察到明显的趋势作为稀土阳离子半径的函数。在杨氏模量和热膨胀的情况下，这些趋势也适用于多组分系统;而多组分系统的热导率明显较低，表明这种材料也有可能充当热障。这些结果为开发新的隔热和环境屏障涂层提供了设计规则，这些涂层的刚度和热膨胀设计为与基材的刚度和热膨胀相匹配，同时具有降低的热导率。
