Li Shouheng, Lin Jinguo, Chen Yun, Luo Zheng, Cheng Haifeng, Liu Feng, Zhang Jin, Wang Shanshan
Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, P. R. China.
Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China.
Small. 2024 Jan;20(4):e2303511. doi: 10.1002/smll.202303511. Epub 2023 Sep 25.
Understanding the growth behavior and morphology evolution of defects in 2D transition metal dichalcogenides is significant for the performance tuning of nanoelectronic devices. Here, the low-voltage aberration-corrected transmission electron microscopy with an in situ heating holder and a fast frame rate camera to investigate the sulfur vacancy lines in monolayer MoS is applied. Vacancy concentration-dependent growth anisotropy is discovered, displaying first lengthening and then broadening of line defects as the vacancy densifies. With the temperature increase from 20 °C to 800 °C, the defect morphology evolves from a dense triangular network to an ultralong linear structure due to the temperature-sensitive vacancy migration process. Atomistic dynamics of line defect reconstruction on the millisecond time scale are also captured. Density functional theory calculations, Monte Carlo simulation, and configurational force analysis are implemented to understand the growth and reconstruction mechanisms at relevant time and length scales. Throughout the work, high-resolution imaging is closely combined with quantitative analysis of images involving thousands of atoms so that the atomic-level structure and the large-area statistical rules are obtained simultaneously. The work provides new ideas for balancing the accuracy and universality of discoveries in the TEM study and will be helpful to the controlled sculpture of nanomaterials.
了解二维过渡金属二硫属化物中缺陷的生长行为和形态演变对于纳米电子器件的性能调谐具有重要意义。在此，应用了配备原位加热支架和快速帧率相机的低电压像差校正透射电子显微镜来研究单层MoS中的硫空位线。发现了空位浓度依赖性生长各向异性，随着空位密度增加，线缺陷先变长然后变宽。随着温度从20°C升高到800°C，由于对温度敏感的空位迁移过程，缺陷形态从密集的三角形网络演变为超长的线性结构。还捕捉到了毫秒时间尺度上线缺陷重构的原子动力学。实施了密度泛函理论计算、蒙特卡罗模拟和构型力分析，以了解相关时间和长度尺度上的生长和重构机制。在整个工作中，高分辨率成像与涉及数千个原子的图像定量分析紧密结合，从而同时获得原子级结构和大面积统计规则。这项工作为平衡透射电子显微镜研究中发现的准确性和普遍性提供了新思路，并将有助于纳米材料的可控雕刻。
