Morphology Control of Two-Dimensional Tin Disulfide on Transition Metal Dichalcogenides Using Chemical Vapor Deposition for Nanoelectronic Applications

Two-dimensional (2D) tin disulfide (SnS2) crystals have been arousing immense attention for flexible electronics and integrated circuits in next generation because of their earth-abundant and nontoxic elemental components. Producing high quality crystal with controlled morphology, however, remains challenging due to the lack of understanding for its growth mechanism. Here, we demonstrate the direct chemical vapor deposition (CVD) growth and morphology control of 2D SnS2 on CVD-grown WS2 layers. In addition to the formation of type II van der Waals (vdW) vertical heterostructures with enhanced charge separation, the morphology of SnS2 is found to be highly dependent on the underlying substrate surface, where lateral growth could be stabilized with epitaxially aligned crystals on the defect-free surface whereas cluster growth appears on the defect-rich surface. This is attributed to the lower energy barrier of migration for adsorbed active species on the defect-free surface, resulting in facilitated surface diffusion compared to the defect-rich surface. Similar results also occur when switching the growth substrates to other 2D transition metal dichalcogenides such as MoS2 layers, showing the importance of defect-free 2D substrates on the SnS2 growth which is crucial for the applications in next-generation nanoelectronics such as photodetectors or light-emitting diodes.