| In modern society,photodetectors,as one of the most important photoelectric devices,have been closely related to human daily life.Photodetector refers to a device that converts optical signals into electrical signals.Photoelectric detectors are classified according to the light frequency they receive,and can be divided into ultraviolet detectors,visible light detectors and infrared detectors.Visible light detectors have been widely used in medical imaging,optical communications,surveillance,remote sensing,and spectral analysis and other fields.Its application prospect and social needs are relatively large.Bi2O3 has special physical properties and crystal morphology.There are seven crystal type,which are marked as?,?,?,?,?,?and?phases respectively.Each crystal type has different crystal structure and physical properties.Bi2O3 is a direct band gap semiconductor.According to the difference of crystal type,its band gap is between 2and 3.96e V.At the same time,Bi2O3 has high refractive index,high dielectric constant,excellent photoconductivity and photoluminescence properties.The luminescence characteristics make Bi2O3 have great development potential in visible light detection.Due to the above unique physical and chemical properties of Bi2O3,the manufacturing process of Bi2O3 thin films and its photodetector performance were studied in this thesis.This research obtained the following results:The thesis uses molecular beam epitaxy(MBE)to study the growth process of Bi2O3 thin film.The crystal structure and morphology of the Bi2O3 thin film were analyzed by X-ray diffraction and scanning electron microscope respectively.The research results of Bi2O3 thin film show that:under optimized growth conditions,a high-quality?-Bi2O3 thin film has been successfully prepared;according to the measurement results of the absorption spectrum of the?-Bi2O3 thin film,the optical band gap of the grown?-Bi2O3 thin film is about 2.88e V.On the basis of the research on the preparation of?-Bi2O3 thin film,the thesis uses electron beam evaporation technology to deposit metal electrodes,and develops a metal-semiconductor-metal(MSM)structure of?-Bi2O3 thin film photoelectric detector.The measurement results show that the device has good photoelectric response to460nm visible light.Under the 10V bias,the optical responsivity reaches 1.15 A/W,and the detection rate reaches 2.31×1011 Jones,indicating that the Bi2O3 thin film has good technical value in the direction of visible light detectors.Based on the study of visible light detection of?-Bi2O3 thin film,Bi2(Se O3)3 thin film was grown by partial substitution of Se for O in this thesis,and its crystal structure,morphology and photoelectric properties were studied.The photodetector with MSM structure was developed by using the grown Bi2(Se O3)3 thin film.Under the 10V bias,the responsivity of the device is 1.32A/W and the detection rate is 7.34×1011 Jones.Based on the study of Bi2O3 and Bi2(Se O3)3 thin film growth and photoelectric response characteristics,Bi2(Se O3)3-Bi2O3 heterojunction was constructed by in-situ deposition method,and the photodiode based on the heterojunction was developed in this thesis.The measurement result of photoelectric response characteristic shows that the responsivity is 0.57A/W and the detection rate is 2.39×1011 Jones under 10V bias. |
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