Preparation Of Pb Se Nanomaterials And Photoelectric Detection Performance

Due to their unique small size effect,nanomaterials exhibit different physicochemical properties from bulk materials,such as optical,mechanical and other properties.New materials are provided for the preparation of new photodetectors with smaller size,lower power consumption and higher response rate.Lead selenide（PbSe）nanomaterials of Ⅳ-Ⅵ group have the characteristics of high modulation bandwidth,low Auger coefficient,and large exciton Bohr radius,and have attracted much attention because of their appropriate band structure and excellent light absorption capacity,and have good prospects for improving the performance of low-dimensional photodetectors.In this paper,the preparation of PbSe nanomaterials by physical vapor deposition was used as the starting point to analyze and characterize the prepared PbSe nanomaterials,and they were prepared into photodetectors and the photoelectric performance of the devices was tested and analyzed.The main contents of the thesis are as follows:（1）The structure of PbSe nanosheets was prepared on fluorphlogopite by physical vapor deposition,and the effects of two key parameters of substrate temperature and pressure in the tube on the growth of PbSe nanosheets were studied.Through comparative experiments,it is found that the PbSe nanosheets are of the best quality when the substrate temperature and pressure in the tube are 500℃ and 500 Pa,respectively.The prepared PbSe nanosheets were characterized in detail with transverse dimensions of around 40μm and thickness of about 60 nm.At the same time,it basically satisfies the atomic metrological ratio of PbSe theory.（2）PbSe nano-thin film photodetector was prepared by vacuum evaporation using oxygen silicon wafer as substrate,and the surface structure of the prepared film was flat and had good uniformity.The prepared PbSe nanosheet structure was transferred to an oxysilicon substrate,and the electrode was designed and evaporated to obtain a PbSe nanosheet photodetector.The photoelectric performance of PbSe nanothin film photodetector and PbSe nanosheet photodetector were tested respectively.Through analysis,in the comparison of key parameters,the specific detection rate of PbSe nanosheets in the 808 nm band was 2.42×10⁸Jones,and the PbSe nanofilms were2.40×10⁷Jones,and PbSe nanosheets were significantly better than PbSe nanofilms.However,PbSe nanosheets also have problems such as excessive dark current and slow response.（3）In order to improve the photoelectric performance of PbSe nanosheet detectors,the two-dimensional material Molybdenum selenide（MoSe₂）was introduced and briefly introduced,and the PbSe/MoSe₂heterostructure was prepared.Through testing,it is found that the dark current of PbSe/MoSe₂devices is significantly improved,and at1 V bias,it is three orders of magnitude lower than that of PbSe nanosheet detectors.At the same time,the response speed is also greatly improved,the decline time is 51.79μs,and the rise time is 54.61μs,which significantly improves the response speed compared with the PbSe nanosheet detector.At the same time,at an optical power density of 20mW/cm²,it has the largest specific detection rate in the 650 nm band,which is1.95×10¹¹Jones.