Preparation And Optical Property Tuning Study Of FeSe Thin Films

Iron-based superconducting materials are high-temperature superconducting materials juxtaposed with copper-oxide superconducting materials.The discovery of iron-based superconducting materials has expanded new ways to solve the internal mechanism of high-temperature superconductivity that has not been understood in the copper oxide stage,and provided a new direction for higher temperature superconductivity and even room temperature superconductivity.Based on the different crystal structures,iron-based superconducting materials are mainly divided into four systems,among them,the typical representative of the "11" system is FeSe superconducting materials.Compared with most other iron-based superconducting materials containing As elements,the preparation and processing process of FeSe without As elements is safer,and it also has the advantages of simple processing methods and low raw material costs.Nowadays,FeSe has become one of the research hotspots of new iron-based superconducting materials.The main contents of this thesis are as follows:Firstly,iron selenide films were prepared on magnesium oxide substrates by magnetron sputtering method,and the effects of deposition temperature,sputtering pressure and film thickness on the crystal structure and surface morphology of FeSe films were mainly characterized by X-ray diffraction and scanning electron microscopy.The influence of annealing time parameters on crystal structure and refractive index was analyzed by X-ray diffraction and ellipsometer tests.After preparing the thin film containing superconducting tetragonal phase-FeSe,the best parameters were selected to prepare the iron selenide thin film and further characterized.Secondly,the optical absorption characteristics of FeSe films are studied.Including the light absorption rate of the monolayer FeSe film and the light absorption rate of the Salisbury screen structure.During the research process,the Salisbury screen structure was mainly designed,simulated,prepared,tested and verified.At the same time,the absorption rate of the sample and the simulation were compared,and the peak-to-peak absorption of the base mode in the simulation and experimental test was more than70 %,which was much greater than the absorption rate of 20 % of the monolayer film,which proved that the structure had a significant enhanced absorption effect.Finally,the simulation and optical transmission characteristics of FeSe metasurface structure are introduced,the FeSe metasurface structure is designed first,and then the refractive index and extinction coefficient of thin film samples are measured by ellipsome,and the metasurface structure model is built by substituting the measured parameters,and its optical transmittance is simulated,and the influence of rectangular block parameters on transmittance,the influence of structural unit period on transmittance,and the influence of different incidence angles on transmittance are analyzed.The simulation results show that the transmittance of the metasurface structure is greater than that of the monolayer film,which proves that the metasurface structure has the effect of enhanced transmission.