Magnetron Sputtering Technology Exploration And Superconducting Properties Optimization Of Fe(Se,Te) Thin Films

The superconductor has an extremely wide application in strong and weak electricity fields due to the unique properties of zero resistance,complete diamagnetism and magnetic flux quantization.The advent of iron-based superconductors undoubtedly further promotes the development and industrial application of superconductors.As one of many families of iron-based superconductors,Fe（Se,Te）superconductor provides the best choice for studying the mechanism of high-temperature superconductivity because of its simple layered structure and weak harm to the environment.At present,a large number of literatures have reported that Fe（Se,Te）superconducting thin films with excellent superconducting properties have been prepared by pulse laser deposition method.However,few literatures reported that Fe（Se,Te）thin films prepared by magnetron sputtering method.Magnetron sputtering coating has the advantages of compact and uniform coating,strong bonding force and low cost.Fe（Se,Te）superconducting thin films prepared on flexible substrates can be used to obtain long superconducting strips with excellent properties,which may realize the large-scale production of Fe（Se,Te）thin films.Nowadays,the fabrication of Fe（Se,Te）superconducting thin films by magnetron sputtering is not mature,and a more suitable sputtering process needs to be further explored.In this paper,the magnetron sputtering method was used to explore the preparation process of Fe（Se,Te）superconducting thin films,and Fe（Se,Te）thin films were deposited on single crystal substrates.The effects of sputtering power,substrate temperature,film thickness and substrate type on electrical transport characteristics of Fe（Se,Te）thin films were studied,and the superconductivity of Fe（Se,Te）films was optimized.The crystal structure,surface morphology,composition and electrical transport characteristics of Fe（Se,Te）thin films were characterized by X-ray diffraction,scanning electron microscope,energy dispersive spectrometer and physical property measurement system,respectively.The main work and results are as follows:1.The substrate temperature,annealing process,film thickness and sputtering power were tested by magnetron sputtering method to explore the preparation technology of Fe（Se,Te）superconducting thin films.The results showed that Fe（Se,Te）thin films with superconductivity were successfully prepared by the substrate temperature of 380 ^oC,sputtering power of 100 W,sputtering time of 60 min and substrate for the Ca F₂.2.The sputtering power and substrate temperature of Fe（Se,Te）superconducting films were optimized.Fe（Se,Te）thin films of different sputtering power（80 W,90 W and 100 W）and different substrate temperatures（320 ^oC,340 ^oC,360 ^oC,and 380 ^oC）were prepared by magnetron sputtering.Studies have shown that the higher the sputtering power,the higher the superconducting transition temperature of the Fe（Se,Te）thin films,the larger the upper critical magnetic field.The higher the substrate temperature,the higher the superconducting initiation transition temperature of Fe（Se,Te）thin films.3.The thickness and substrate type of Fe（Se,Te）superconducting films were optimized.Fe（Se,Te）thin films of different thicknesses（500 nm,1μm and 2μm）and different substrates（La Al O₃,Mg O,Sr Ti O₃ and Ca F₂）were deposited using magnetron sputtering.The study found that the thicker the thin films,the higher the superconducting initiation transition temperature and the superconducting zero resistance temperature of Fe（Se,Te）thin films,the better superconducting properties in high magnetic field.Among Fe（Se,Te）thin films grown on different substrates,only the film deposited on the Ca F₂ substrate exhibits a superconducting signal.The Ca F₂ single crystal substrate may be more advantageous to form the superconducting phase of Fe（Se,Te）thin films.