Modification Of Two-Dimensional WS₂ Atomic Crystals By Thermal Evaporation Assisted CVD Method

Two-dimensional transition metal dichalcogenides（TMDCs）as a new type of two-dimensional nanomaterial have attracted widespread attention due to their unique structure and excellent optoelectronic properties.Tungsten disulfide（WS₂）is a typical representative of TMDCs,with features such as high luminescence efficiency and narrow emission peak,exhibiting great potential in many fields,especially in the research of WS₂ modification through doping,heterostructures,etc.,which has been a research hotspot in recent years.However,controlling the modification of WS₂ remains a significant challenge,making it crucial to seek a universal and straightforward modification method.In this study,a synthesis strategy of the thermal evaporation-assisted chemical vapor deposition（CVD）method was proposed to modify two-dimensional WS₂,mainly achieving controllable preparation of doped and heterostructured WS₂,including the following three parts:1.Preparation of WO_x nanowires as precursors to achieve the controllable synthesis of WS₂.Using the thermal evaporation method to prepare low-melting WO_xnanowire structures as tungsten sources,high-purity,high-quality,large-area single-layer WS₂ was controllably synthesized through CVD.2.Incorporating the dopant source into the tungsten source to achieve high-concentration doping of WS₂.W_xV_yO_z nanowires were prepared as precursors through thermal evaporation,and V-doped WS₂ was synthesized through CVD method.The influence of different factors on the experimental results was studied,and finally,controllable preparation of V-doped WS₂ was achieved.Analysis and characterization of its electrical properties showed that with the doping of V,the photoluminescence of WS₂ was quenched,and the carrier type changed from n-type to p-type.Meanwhile,Nb-doped WS₂ was also studied,demonstrating the universality of using metal oxide nanowires as precursors to prepare doped WS₂.3.Constructing a precursor with a core-shell structure to prepare heterostructures.This study used a two-step thermal evaporation method to prepare WO_x/Re O_xnanowires with a core-shell structure as precursors,and WS₂/Re S₂ heterostructures were prepared through CVD method.The morphology and structure of the heterostructure were characterized,proving the feasibility of this strategy in constructing heterostructures.