• Saien Xie, Lijie Tu, Yimo Han, Lujie Huang, Kibum Kang, Ka Un Lao, Preeti Poddar, Chibeom Park, David A Muller, Robert A DiStasio, and Jiwoong Park.
• School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.
• Science. 2018 Mar 9; 359 (6380): 1131-1136.

AbstractEpitaxy 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.Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

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