Preparation Of Co-sputtered Ag-MoSe₂ Film Material And Study On Nonlinear Optical Properties

In recent years,in view of the need for materials with excellent optical and electrical properties in the field of optoelectronic devices,there has been great interest in layered transition metal sulfides(TMDs).Many TMDs materials have strong excitonic characteristics,and exhibit strong and narrow photoluminescence and absorption characteristics,making them very suitable for the research of new optoelectronic devices.For example:optical limiter,optical communication,optical switch,etc.The band gap(1-2 e V)and the versatility of atomic composition also make TMDs an ideal material for microelectronics.MoSe₂ based on the characteristics of narrow band gap,smaller line width,and adjustable exciton charge effect,makes it exhibit excellent chemical,physical and optical properties in practical applications.At the same time,the carrier migration speed of the MoSe₂ film is low,and transition metals(such as platinum,silver and iron)can improve the carrier migration speed of semiconductor materials.Therefore,the use of doping or compounding control methods can improve the photoelectric properties of the material.In this thesis,magnetron sputtering was used to obtain Ag-MoSe₂ composite films under different conditions(deposition time,radio frequency(RF)power,substrate temperature),and the morphology,composition and structural characteristics of the samples were characterized and analyzed.The linear and nonlinear optical(NLO)characteristics were studied furtherly.The main results of the research are as follows:(1)First,the co-sputtering technology is used to design and prepare Ag-MoSe₂ films with different experimental parameters,and the dependence of the morphology,composition,structure and experimental parameters of the Ag-MoSe₂ film is analyzed.Scanning electron microscopy(SEM)results confirmed that:RF power,deposition time and substrate temperature all affect the morphology,structure and thickness of Ag-MoSe₂ films.RF power affects the surface morphology of the Ag-MoSe₂ film.With the increase of RF power,clusters appear on the surface of the film.The deposition time affects the thickness and compactness of the film,and the thickness and compactness of the film increase with the increase of the deposition time.The substrate temperature affects the crystalline quality of the film.The higher the substrate temperature,the higher the crystalline quality of the film.XRD patterns confirmed the influence of RF power and substrate temperature on the structure of Ag-MoSe₂ films.With the increase of RF power,the Ag-MoSe₂ film appears amorphous.The higher the substrate temperature,the stronger the XRD peak intensity.The chemical composition and valence state of Ag-MoSe₂ film were analyzed by photoelectron spectroscopy(EDS)and X-ray photoelectron spectroscopy(XPS).The results show that there are characteristic peaks of Ag⁺,Mo⁴⁺and Se^2-in the film.(2)Secondly,study the linear ultraviolet-visible light absorption spectrum and band gap structure of Ag-MoSe₂ film.The band gap values of Ag-MoSe₂ thin film materials under different RF powers are obtained by calculation.The results show that the band gap values of Ag-MoSe₂ films with different RF powers are 1.84 e V(80 W),1.84 e V(90 W)and 1.83 e V(100 W),respectively.Moreover,the Ag content has a significant modulation effect on the light absorption characteristics of the Ag-MoSe₂ composite film.By analyzing the photoluminescence spectrum of the Ag-MoSe₂ film,it is known that the substrate temperature has a promoting effect on the luminescence characteristics of the film.(3)Finally,Z-scan was used to test the NLO properties of the Ag-MoSe₂ film.The nonlinear absorption(NLA)coefficient is calculated and its physical mechanism is revealed.The experimental results show that the Z-scan of the Ag-MoSe₂ film exhibits saturated absorption induced by a single photon.Under different RF powers,as the RF power increases,the NLA coefficient first decreases and then increases.Under different deposition times,the NLA coefficient increases with the increase of deposition time.