Preparation And Optical Properties Of Tungsten Disulfide Thin Films

Transition metal chalcogenide?TMDCs?single-layer material with adjustable direct band gap of 1² e V,crystal structure of graphene-like,so that based on this series of materials,it can be assembled into planar thin film transistors and light-emitting transistors with excellent performance.,photodetectors,solar cells and other devices.In this paper,we first studied the controllable preparation of large-size high-quality WS₂ thin film CVD method.The WS₂ thin film was prepared by orthogonal experiment,and the reaction temperature,reaction time,argon flow rate and sulfur-tungsten ratio were investigated by range analysis method.The area effect of the prepared film.The specific research contents are as follows:Firstly,the ordinary CVD method was used to optimize the preparation parameters of large-area WS₂ film by orthogonal design.The photoluminescence properties of large-area WS₂ film under optimized process were studied.The results show that the optimized process parameters are:growth temperature 830°C,growth time 10 min,argon flow rate 60 sccm,sulfur to tungsten ratio 3:1,under this set of conditions,a large area of continuous single-layer film is grown on the substrate..Temperature is the most important factor affecting the growth area of the film,followed by time,argon flow rate,sulfur to tungsten ratio.In the orthogonal experiment,a large number of triangular films were deposited on the substrate under the conditions of a reaction temperature of 800°C,a reaction time of 20 minutes,an argon gas flow rate of 60 sccm,and a sulfur to tungsten ratio of 3:1.The unilateral size was generally above 40?m.The largest one of the dies has a length of about 50?m and is a multilayer film.The single-layer film prepared under the conditions of growth temperature of 830°C,growth time of 10 min,argon flow rate of 60 sccm and sulfur to tungsten ratio of 3:1 has the highest luminescence peak intensity,indicating that the film prepared by the process has the highest crystal quality.Secondly.The large-size high-quality WS₂ film was prepared by sodium chloride and potassium chloride assisted CVD.The results show that the metal halides contribute to the continuous film formation,and the film preparation is better.However,the films grown by the auxiliary method are mostly Multilayer WS₂ film.A large-area single-layer film having a size of about 53?m was prepared under the conditions of 3 mg sodium chloride assisted film preparation,and was the largest single-layer single-particle film prepared herein.