The Preparation And Photovoltaic Properties Of La Doped Ferroelectric BiFeO₃ Thin Films

In recent years as smartphones,tablets,wearable devices such as consumer electronics is becoming more and more popular,the demand for chips,display devices and optical sensor is increasing,and the upgrading of products depends on the continuous development of semiconductor materials,the actual production and life of semiconductor materials and semiconductor device put forward higher requirements.Due to its excellent physical properties,ferroelectric materials have a broad application prospect in the field of multifunctional devices.The ferroelectric material BiFeO₃ has both the ferroelectric properties of ferroelectric materials and the energy band structure of semiconductor materials,which gives it great application potential and attracts the attention of researchers.However,in practice,there are still many deficiencies in ferroelectric BiFeO₃ material,which limit its application.Relevant reports indicate that doping rare earth elements can effectively improve the performance of BiFeO₃ thin film.In this paper,doping La in BiFeO₃ thin film is selected to improve the performance of the thin film,so as to prepare BiFeO₃/ZnO heterojunction ULTRAVIOLET photoelectricity detector with good performance.Firstly,a group of La doped BiFeO₃ films with different drying time were successfully prepared by sol-gel method,and the prepared BiFeO₃ films were tested by XRD and transmission spectrum.XRD test results show that the ferroelectric BiFeO₃ thin films with La doping concentration of 10% are indeed prepared by sol-gel method.The ultraviolet-visible transmission spectrum?UV-VIS?test showed that the thin film had good optical performance,and the La doping could be judged to widen the optical band gap of BiFeO₃ thin film by the position movement of the absorption edge.According to the transmission spectrum,the optical band gap of the film is calculated by using the linear extrapolation method.The optical band gap of the prepared La doped BiFeO₃ film is about 2.5e V,which proves again that La doping broadfies the optical band gap of BiFeO₃ film.In order to further study the La doping widened BiFeO₃ thin film optical properties,paper kramer-krone Ge relationship as the starting point,through a series of mathematical deduction got through the calculation of thin film transmission spectra of a series of formulas and methods of thin film optical constants.Based on the derived formula,a set of program for calculating semiconductor optical constants was written in Python language,and an effective method for obtaining semiconductor optical properties was developed.Semiconductor optical constants by calculation of written procedures for the preparation of good BiFeO₃ film transmission spectra data for the calculation of optical constants,success in getting our preparation of La doping ferroelectric BiFeO₃ optical constants of thin film?film refractive index and absorption coefficient,extinction coefficient,dielectric constant of real part and imaginary part of dielectric constant?,and the calculation results are analyzed.Then the optical constants of a group of La doped ferroelectric BiFeO₃ films with different drying times were calculated,and the optical properties of the films were studied,and the influence of different drying times on the optical properties of the prepared La doped ferroelectric BiFeO₃ films was analyzed.In order to study the photoelectric performance of BiFeO₃/ZnO heterojunction UV photoelectricity detector,this paper USES Silvaco TCAD's TWO-DIMENSIONAL device simulator ATLAS to simulate and design our heterojunction UV photoelectricity detector consisting of La doped ferroelectric BiFeO₃ thin film and ZnO,and gives the designed structure design of the detector for subsequent simulation experiments.Then the rectifier effect and photoelectric detection performance of BiFeO₃/ZnO heterojunction UB photoelectricity detector were simulated by two-dimensional device simulator ATLAS.In order to further analyze the influence of the energy band structure of the device on its electrical response,we drew a schematic diagram of the energy band structure of Pt/BiFeO₃/ZnO/ITO device,and analyzed the electrical test results of the device according to the energy band structure diagram of the device.In order to simulate the photoelectric performance of the device,the experiment further simulated the IV response of the device under ultraviolet light with the two-dimensional device simulator of the software,and studied the photoelectric detection performance of the device.Paper explores BiFeO₃/ZnO heterojunction UV photodetectors at different wavelength of incident light of light intensity under the irradiation of the photoelectric performance,and the paper also studied the BiFeO₃ and two other semiconductor heterojunction formed by the performance of the detector,respectively using two dimensional device simulator simulates the BiFeO₃/ZnSe heterojunction photoelectric device and BiFeO₃/ZnS heterojunction administered photoelectric performance of photoelectric device.The research content of this paper is of great significance to the performance improvement and application expansion of ultraviolet photoelectricity detector.