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

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, 1L-MoS2/1L-WS2, 4L-MoS2/2L-WS2, 4L-MoxW1-xS2/3L-WS2, and 1L-MoxW1-xS2/2L-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.