Defect Agglomeration and Electron-Beam-Induced Local-Phase Transformations in Single-Layer MoTe2

Atom migrations in single-layer 1H-MoTe2 are studied with Cc/Cscorrected high-resolution transmission electron microscopy at an electron energy of 40 keV using the electron beam simultaneously for material modification and imaging. After creating tellurium vacancies and vacancy lines, we observe their migration pathways across the lattice. Furthermore, we analyze phase transformations from the 1Hto the 1T′-phase associated with the strain induced due to the formation of Te vacancy lines. Combining the experimental data with the results of first-principles calculations, we explain the energetics and driving forces of pointand line-defect migrations and the phase transformations due to an interplay of electron-beam-induced energy input, atom ejection, and strain spread. Our results enhance the understanding of defect dynamics in 2D transition metal dichalcogenides, which should facilitate tailoring their local optical and electronic properties.

利用Cc/Cs校正的高分辨率透射电子显微镜，在40 keV的电子能量下，同时使用电子束进行材料改性和成像，研究了单层1H - MoTe₂中的原子迁移。在产生碲空位和空位线之后，我们观察到它们在晶格中的迁移路径。此外，我们分析了与碲空位线形成所引起的应变相关的从1H相到1T′相的相变。将实验数据与第一性原理计算结果相结合，我们解释了点缺陷和线缺陷迁移的能量学和驱动力，以及由于电子束诱导的能量输入、原子喷射和应变传播的相互作用而导致的相变。我们的研究结果增进了对二维过渡金属二硫化物中缺陷动力学的理解，这将有助于定制它们的局部光学和电子性质。