Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas, 75080, United States.
School of Advanced Materials, Kookmin University, Jeongneung-gil 77, Seongbuk-gu, Seoul, 136-702, Korea.
Sci Rep. 2017 Jun 7;7(1):2977. doi: 10.1038/s41598-017-02919-2.
Controlled growth of crystalline solids is critical for device applications, and atomistic modeling methods have been developed for bulk crystalline solids. Kinetic Monte Carlo (KMC) simulation method provides detailed atomic scale processes during a solid growth over realistic time scales, but its application to the growth modeling of van der Waals (vdW) heterostructures has not yet been developed. Specifically, the growth of single-layered transition metal dichalcogenides (TMDs) is currently facing tremendous challenges, and a detailed understanding based on KMC simulations would provide critical guidance to enable controlled growth of vdW heterostructures. In this work, a KMC simulation method is developed for the growth modeling on the vdW epitaxy of TMDs. The KMC method has introduced full material parameters for TMDs in bottom-up synthesis: metal and chalcogen adsorption/desorption/diffusion on substrate and grown TMD surface, TMD stacking sequence, chalcogen/metal ratio, flake edge diffusion and vacancy diffusion. The KMC processes result in multiple kinetic behaviors associated with various growth behaviors observed in experiments. Different phenomena observed during vdW epitaxy process are analysed in terms of complex competitions among multiple kinetic processes. The KMC method is used in the investigation and prediction of growth mechanisms, which provide qualitative suggestions to guide experimental study.
控制晶体的生长对于器件应用至关重要，已经开发出了用于体相晶体的原子级建模方法。动力学蒙特卡罗（KMC）模拟方法可以在真实的时间尺度上提供晶体生长过程中的详细原子级过程，但尚未将其应用于范德华（vdW）异质结构的生长建模。具体来说，单层过渡金属二卤化物（TMD）的生长目前面临巨大的挑战，基于 KMC 模拟的详细理解将为控制 vdW 异质结构的生长提供关键指导。在这项工作中，开发了一种用于 TMD 的 vdW 外延生长建模的 KMC 模拟方法。该 KMC 方法在自下而上的合成中引入了 TMD 的完整材料参数：金属和硫属元素在衬底和生长的 TMD 表面上的吸附/解吸/扩散、TMD 的堆积序列、硫属元素/金属比、薄片边缘扩散和空位扩散。KMC 过程导致了与实验中观察到的各种生长行为相关的多种动力学行为。在 vdW 外延过程中观察到的不同现象，可以通过多种动力学过程之间的复杂竞争来分析。KMC 方法用于研究和预测生长机制，为指导实验研究提供了定性建议。
