Understanding the growth mechanisms of 2D van der Waals (vdW) heterostructures is of great importance in exploring their functionalities and device applications. A custom-built system integrating physical vapor deposition and optical microscopy/Raman spectroscopy is employed to study the dynamic growth processes of 2D vdW heterostructures in situ. This allows the identification of a new growth mode with a distinctly different growth rate and morphology from those of the conventional linear growth mode. A model that explains the difference in morphologies and quantifies the growth rates of the two modes by taking the role of surface diffusion into account is proposed. A range of material combinations including CdI2 /WS2 , CdI2 /MoS2 , CdI2 /WSe2 , PbI2 /WS2 , PbI2 /MoS2 , PbI2 /WSe2 , and Bi2 Se3 /WS2 is systematically investigated. These findings may be generalized to the synthesis of many other 2D heterostructures with controlled morphologies and physical properties, benefiting future device applications.
Keywords: 2D heterostructures; epitaxial growth; growth dynamics; van der Waals heterostructures.
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