Flat Bands and Mechanical Deformation Effects in the Moire Superlattice of MoS2-WSe2 Heterobilayers
Flat Bands and Mechanical Deformation Effects in the Moire Superlattice of MoS2-WSe2 Heterobilayers
复制标题
MoS2-WSe2 异质双层莫尔超晶格中的平带和机械变形效应
DOI：
10.1021/acsnano.0c03414
复制
发表时间：
2020
期刊：
影响因子：
17.1
通讯作者：
all M.
中科院分区：
文献类型：
--
作者：
Waters Dacen;Nie Yifan;Lupke Felix;Pan Yi;Foelsch Stefan;Lin Yu-Chuan;Jariwala Bhakti;Zhang Kehao;Wang Chong;Lv Hongyan;Cho Kyeongjae;Xiao Di;Robinson Joshua A.;Feenstra R;all M.
最近的研究表明，在外延生长的范德瓦尔斯材料异质层中可以出现量子限制态，而不存在旋转错位（θ = 0°），这与由于两层晶格不匹配而形成的莫尔条纹布里温区中的平带有关。仅考虑导致能带边缘能量空间变化的局部堆叠排列，定性地描述了MoS2/ wse2体系中局部态密度和约束峰。在这项工作中，我们报告了在θ = 0°MoS2/ wse2异质层的波纹单元胞中存在较大的面内应变变化，并表明在密度泛函理论计算中包含应变变化和面外位移大大提高了它们与实验数据的一致性。我们进一步探讨了扭转角的作用，并展示了扭转角为θ = 15°时扭曲的MoS2/ wse2异质层结构的实验数据，该结构呈现出波纹模式，但没有约束。
It has recently been shown that quantum-confined states can appear in epitaxially grown van der Waals material heterobilayers without a rotational misalignment (θ = 0°), associated with flat bands in the Brillouin zone of the moiré pattern formed due to the lattice mismatch of the two layers. Peaks in the local density of states and confinement in a MoS2/WSe2system was qualitatively described only considering local stacking arrangements, which cause band edge energies to vary spatially. In this work, we report the presence of large in-plane strain variation across the moiré unit cell of a θ = 0° MoS2/WSe2heterobilayer and show that inclusion of strain variation and out-of-plane displacement in density functional theory calculations greatly improves their agreement with the experimental data. We further explore the role of a twist angle by showing experimental data for a twisted MoS2/WSe2heterobilayer structure with a twist angle of θ = 15°, which exhibits a moiré pattern but no confinement.