Coherent strained superlattices Two-dimensional superlattices represent the atomic-thickness limit of heterostructures that enable technologies such as strain-engineered multiferroics and quantum-cascade lasers. Xie et al. were able to produce monolayer superlattices of transition metal dichalcogenides (WS2 and WSe2) with full lattice coherence, despite a 4% lattice mismatch. They used a modulated metal-organic chemical vapor deposition process that precisely controlled each precursor. Furthermore, the authors could strain-engineer the optical properties of the superlattices to observe out-of-plane rippling. Science, this issue p. 1131 Omnidirectional epitaxy produced superlattices with strain-engineered optical properties and mechanical deformations. Epitaxy forms the basis of modern electronics and optoelectronics. We report coherent atomically thin superlattices in which different transition metal dichalcogenide monolayers—despite large lattice mismatches—are repeated and laterally integrated without dislocations within the monolayer plane. Grown by an omnidirectional epitaxy, these superlattices display fully matched lattice constants across heterointerfaces while maintaining an isotropic lattice structure and triangular symmetry. This strong epitaxial strain is precisely engineered via the nanoscale supercell dimensions, thereby enabling broad tuning of the optical properties and producing photoluminescence peak shifts as large as 250 millielectron volts. We present theoretical models to explain this coherent growth and the energetic interplay governing the ripple formation in these strained monolayers. Such coherent superlattices provide building blocks with targeted functionalities at the atomically thin limit.

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具有工程应变的相干、原子级薄的过渡金属二硫属化物超晶格

相干应变超晶格 二维超晶格代表异质结构的原子厚度极限，它支持应变工程多铁性和量子级联激光器等技术。谢等人。尽管存在 4% 的晶格失配，但能够产生具有完全晶格相干性的过渡金属二硫属化物（WS2 和 WSe2）的单层超晶格。他们使用调制的金属有机化学气相沉积工艺来精确控制每个前体。此外，作者可以对超晶格的光学特性进行应变工程，以观察面外波纹。科学，这个问题 p。1131 全向外延产生具有应变工程光学特性和机械变形的超晶格。外延形成现代电子学和光电子学的基础。我们报告了相干的原子级薄超晶格，其中不同的过渡金属二硫属化物单层（尽管晶格失配大）重复并横向集成，单层平面内没有位错。通过全向外延生长，这些超晶格在异质界面上显示出完全匹配的晶格常数，同时保持各向同性晶格结构和三角对称性。这种强外延应变是通过纳米级超胞尺寸精确设计的，从而能够对光学特性进行广泛的调整，并产生高达 250 毫电子伏特的光致发光峰位移。我们提出了理论模型来解释这种相干生长和控制这些应变单层中波纹形成的能量相互作用。