J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague, Czech Republic.
Materials Science Factory, Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain.
ACS Nano. 2023 Apr 25;17(8):7787-7796. doi: 10.1021/acsnano.3c00609. Epub 2023 Apr 6.
We investigate the intrinsic strain associated with the coupling of twisted MoS/MoSe heterobilayers by combining experiments and molecular dynamics simulations. Our study reveals that small twist angles (between 0 and 2°) give rise to considerable atomic reconstructions, large moiré periodicities, and high levels of local strain (with an average value of ∼1%). Moreover, the formation of moiré superlattices is assisted by specific reconstructions of stacking domains. This process leads to a complex strain distribution characterized by a combined deformation state of uniaxial, biaxial, and shear components. Lattice reconstruction is hindered with larger twist angles (>10°) that produce moiré patterns of small periodicity and negligible strains. Polarization-dependent Raman experiments also evidence the presence of an intricate strain distribution in heterobilayers with near-0° twist angles through the splitting of the E mode of the top (MoS) layer due to atomic reconstruction. Detailed analyses of moiré patterns measured by AFM unveil varying degrees of anisotropy in the moiré superlattices due to the heterostrain induced during the stacking of monolayers.
我们通过实验和分子动力学模拟相结合，研究了扭曲的 MoS/MoSe 异质双层耦合所产生的固有应变。研究表明，小的扭转角（0 到 2°之间）会导致显著的原子重构、大的莫尔周期和高水平的局域应变（平均约为 1%）。此外，莫尔超晶格的形成受到特定的堆叠域重构的辅助。这个过程导致了一种复杂的应变分布，其特征是具有单轴、双轴和剪切分量的组合变形状态。随着扭转角的增大（>10°），晶格重构受到阻碍，莫尔图案的周期性减小，应变可忽略不计。通过原子重构导致顶部（MoS）层 E 模的分裂，偏振相关的拉曼实验也证明了近 0°扭转角异质双层中存在复杂的应变分布。通过原子力显微镜测量的莫尔图案的详细分析揭示了由于在堆叠单层过程中产生的异质应变，莫尔超晶格具有不同程度的各向异性。
