Controllable Synthesis\nof WSe₂–WS₂ Lateral Heterostructures\nvia Atomic Substitution

Abstract

The atomic substitution in two-dimensional (2D) materials\nis propitious\nto achieving compositionally engineered semiconductor heterostructures.\nHowever, elucidating the mechanism and developing methods to synthesize\n2D heterostructures with atomic-scale precision are crucial. Here,\nwe demonstrate the synthesis of monolayer WSe₂–WS₂ heterostructures with a relatively sharp interface from monolayer\nWSe₂ using a chalcogen atom-exchange synthesis route at\nhigh temperatures for short periods. The substitution was initiated\nat the edges of monolayer WSe₂ and the lateral diffuse\nalong the heterointerface, and the reaction can be controlled by the\nprecise reaction time and temperature. The lateral heterostructure\nand substitution process are studied by Raman and photoluminescence\n(PL) spectroscopies, electron microscopy, and device characterization,\nrevealing a possible mechanism of strain-induced transformation. Our\nfindings demonstrate a highly controllable synthesis of 2D layered\nmaterials through atom substitutional chemistry and provide a simple\nroute to control the atomic structure.