Controlled Key Factors Of Chemical Vapor Deposition For Two-Dimensional Transition Metal Dichalcogenides Growth

Transition metal dichalcogenides?TMDs?is a typical two-dimensional layered material with a certain band gap.It has attracted interesting attention due to its unique physical and chemical properties,which make it be applied widely in various aspects,including electronic device,energy storage,catalytic hydrogen evolution,and so on.In this paper,based on chemical vapor deposition,low pressure chemical vapor deposition?LPCVD?method is improved to growing the MoS₂ and ReS₂ crystals,and then the key factors of growth were effectively controlled in the process of LPCVD growth.High-quality MoS₂ crystals are steady synthesized in wide process window,using the milled mixtures of MoO₃ and NaCl compound as the precursors,where the melting point of molybdenum precursor is significantly reduced,and thus the reaction concentration of the precursor is improved in low temperature.On the other hand,high-quality and large-size MoS₂ flakes are achieved by reducing the nucleation density of MoS₂ crystals originating from the constructed micro-reactors.Importantly,the high-yield growth can be realized via many micro-reactors stacked each other.And the MoS₂-based field effect transistor showed superior electrical properties,the electron mobility is up to 25 cm²/?V·s?,and the current on/off ratio is 10⁶.In addition,as far as the growth of ReS₂ material with unique crystal structure different from general TMDs,the out-of-plane growth of ReS₂ crystal is successfully suppressed,and then the high-quality ReS₂ flakes are grown on the SiO₂/Si substrate via using the facile vacuum transport method and the strategy of improved substrate surface oxidation treatment.