Lateral WSe₂/MoSe₂ Heterostructures Grown by a Two-step CVD Method

Recently, atomically thin transition metal dichalcogenides (TMDs), as well as their heterostructures, have attracted great attention due to their unique properties. In this work, we systematically investigate the impact of the growth conditions on the morphology of the MoS₂ and WSe₂ grown by chemical vapor deposition (CVD) using solid precursors. Large domain sizes (100 μm) of WSe₂ are synthesized. We further demonstrate WSe₂/MoSe₂ heterostructure growth by using a two-step CVD method, where MoS₂ was synthesized first followed by an epitaxial growth of WSe₂ on the edge. During the WSe₂ growth, a Se–S ion exchange occurs in the MoS₂ region, converting the MoS₂ into MoSe₂. The Raman and photoluminescence spectra, and atomic force microscope (AFM) images, of the synthesized structure indicate that the film is a monolayer lateral heterostructure. These heterostructures will have broad application in nanoscale electronic and photonic devices, including tunneling field effect transistors, photodetectors, and solar cells.