Xu Jiangang, Srolovitz David J, Ho Derek
Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China.
ACS Nano. 2021 Apr 27;15(4):6839-6848. doi: 10.1021/acsnano.0c10474. Epub 2021 Mar 22.
The two-dimensional (2D) transition metal dichalcogenide (TMD) MoS possesses many intriguing electronic and optical properties. Potential technological applications have focused much attention on tuning MoS properties through control of its morphologies during growth. In this paper, we present a unified spatial-temporal model for the growth of MoS crystals with a full spectrum of shapes from triangles, concave triangles, three-point stars, to dendrites through the concept of the adatom concentration profile (ACP). We perform a series of chemical vapor deposition (CVD) experiments controlling adatom concentration on the substrate and growth temperature and present a method for experimentally measuring the ACP in the vicinity of growing islands. We apply a phase-field model of growth that explicitly considers similar variables (adatom concentration, adatom diffusion, and noise effects) and cross-validate the simulations and experiments through the ACP and island morphologies as a function of physically controllable variables. Our calculations reproduce the experimental observations with high fidelity. The ACP is an alternative paradigm to conceptualize the growth of crystals through time, which is expected to be instrumental in guiding the rational shape engineering of MoS crystals.
二维（2D）过渡金属二硫属化物（TMD）MoS具有许多引人入胜的电子和光学特性。潜在的技术应用通过在生长过程中控制其形态来调节MoS特性，这引起了人们的广泛关注。在本文中，我们通过引入吸附原子浓度分布（ACP）的概念，提出了一个统一的时空模型，用于描述MoS晶体从三角形、凹三角形、三点星形到枝晶等全形状谱的生长过程。我们进行了一系列化学气相沉积（CVD）实验，控制衬底上的吸附原子浓度和生长温度，并提出了一种实验测量生长岛附近ACP的方法。我们应用了一个生长相场模型，该模型明确考虑了类似的变量（吸附原子浓度、吸附原子扩散和噪声效应），并通过ACP和岛形态作为物理可控变量的函数，对模拟和实验进行交叉验证。我们的计算以高保真度再现了实验观测结果。ACP是一种通过时间来概念化晶体生长的替代范式，有望在指导MoS晶体的合理形状工程方面发挥作用。
