CVD-growth and interlayer interaction of multilayer WS2-based vertical heterostructures with the evolution of bottom section from MoS2 to alloyed MoxW1-xS2

Abstract

The construction of vertical van der Waals (vdW) heterostructures (HSs) via stacking various two-dimensional (2D) transition-metal dichalcogenide (TMDC) crystals supplies an alternative pathway to modifying relative physical characteristics through a transfer method. However, fabrication of 2D multilayer TMDC vdW HSs is still challenging by a one-step chemical vapor deposition (CVD). In this work, high-yield 2D TMDC vdW HSs, for example, 1 L-MoS2/1 L-WS2, 4 L-MoS2/2 L-WS2, 4 L-MoxW1-xS2/3 L-WS2, and 1 L-MoxW1-xS2/2 L-WS2, have been realized through a strategy combining the precursors’ spin-coating and one-step CVD method. The structure, composition distribution, exciton behavior, and interlayer interaction of these unique multilayer vdW HSs are systematically estimated by optical microscopy, atomic force microscopy, and Raman/photoluminescence measurements. We further reveal the effect of layer number and compositions on the evolution of interlayer exciton in the range of 848–955 nm, and the possible growth mechanism of as-grown WS2-based multilayer vdW HSs. Our results demonstrate the prospects of regulating light emission from interlayer excitons and facilitate the development of novel optoelectronics based on multilayer 2D TMDC vdW HSs.