Heterosite Nucleation Growth of 2D Multilayer Mo 1– x W x S 2 -Based Vertical Heterostructures via a Spin-Coated-Precursor-Mediated CVD Approach

Two-dimensional (2D) vertical heterostructures (HSs) based on 2D transition metal dichalcogenide (TMDC) alloys provide an alternative strategy to modulate fundamental properties by tuning the compositions and then expanding possible device applications. However, achieving controllable chemical vapor deposition (CVD) preparation of 2D TMDC alloy vdW HSs remains an enormous challenge, which has a remarkable influence on the physical properties and device performance. Here, we demonstrated a one-step CVD growth of high-yield 2D multilayer vdW HSs consisting of WS 2 and Mo 1– x W x S 2 crystals with various compositions and heterosite nucleation by employing spin-coated Mo/W precursors on the growth substrate. All 2D multilayer vdW HSs were confirmed to contain the 2D Mo 1– x W x S 2 flake as the bottom section and the 2D WS 2 flake as the top part, and they presented different nucleation sites. The variation of characteristic peaks from position-dependent Raman, photoluminescence, and ultralow Raman spectra elucidated the composition, phase, and interlayer interaction change in such special vdW HSs. Moreover, the potential growth mechanism of these distinctive structures is elucidated by analyzing the evolution of the spin-coating Mo-to-W atomic ratio. The successful growth of 2D multilayer TMDC vdW HSs with heterosite nucleation, achieved in this work, paves the way for their application in future micronano-optoelectronics.