Coherent, atomically thin transition-metal dichalcogenide superlattices with engineered strain

Abstract

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.

Real-space light-reflection mapping of atomically thin WSe2 flakes revealing the gradient local strain

“…Recently, many studies have been reported on the strain effect of 2D layered materials [10][11][12]. This effect has been proved that the optical band gap can be tuned by up to several hundred meV/% in atomically thin TMDs by local strain [13].…”

Tunable Electronic Properties and Potential Applications of 2D GeP/Graphene van der Waals Heterostructure

“…The heterostructures of 2D materials with graphene also induce the change of graphene's shape and the configuration of the heterostructures, giving rise to novel electronic and photoelectric properties 2,33,34. More importantly, the electronic and optical performances of 2D semiconductors can be further tuned by strain engineering for device applications 35,36…”

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

“…This progress is clearly reflected in the description of HSs systems, which has changed from alloys to interfaces. Recent experiments have shown remarkable control on sharpness [37] and strain at the interface [36,38]. Moreover, atomically sharp interfaces between crystalline phases of the same TMD, 1T'-WSe 2 and 1H-WSe 2 , have been studied in the search for topologically protected helical edge states [39].…”