| Since Graphene was discovered,it has rapidly become a research hotspot in materials science,physics and electronics due to its unique structure and excellent properties.Due to its extremely high carrier mobility and wide spectral absorption capacity in the ultraviolet to infrared band,graphene has attracted extensive attention in the research of photodetector and become the preferred material for the channel of photoelectric devices.However,as a monolayer two-dimensional material,graphene has a low photoabsorptivity and a fast photoexcited carrier recombination,which limits its current development in the field of photodetectors.To solve these problems,researchers have explored many other new two-dimensional materials with similar to graphene.Molybdenum sulfide,as one of these new two-dimensional mater:ials,has excellent photoelectric properties,attracting many researchers to use it in the preparation of photodetector.But molybdenum sulfide photodetector also has some shortcomings,such as the electron in molybdenum sulfide in the transmission rate is short,molybdenum sulfide absorbance is low,resulting in the current two-dimensional material detector performance is not ideal.In response to the above problems,researchers are constantly exploring new methods,such as the preparation of new graphene-like materials,and the preparation of graphene and other composite materials with excellent properties.Among them,lead sulfide,as a low-dimensional photoelectric material with high absorbance,is often used to compound with graphene.This composite material can not only protect the excellent performance of graphene from damage,but also make up for the inherent shortcomings of graphene,so as to improve the light absorption ability of graphene photodetector.In view of the above backgroproperties und,this paper mainly studies the preparation of the three-dimensional molybdenum sulfide photodetector with a vertical orientation of the composite material of lead sulfide and graphene.Through the design and optimization of the process parameters,the improved photodetector effectively enhances the photoelectric properties of the traditional graphene and molybdenum sulfide photodetectors.The main results of this paper are as follows:(1)Preparation and properties of single crystal graphene photodetectors by chemical vapor deposition Large area single crystal graphene films were prepared by chemical vapor deposition,and the maximum diameter of the graphene single crystal films could reach 80 ?m.The photoelectric response of the photodetector prepared by the grown graphene film can reach 18 mAW-1;(2)Preparation of lead sulfide/graphene composite photodetector by electrochemical method and its propertiesThe electrochemical deposition method was used to deposit lead sulfide nano-column on the graphene surface in situ,and the new material combining lead sulfide and graphene was used to prepare the photodetector.The test shows that the photodetector has the characteristics of wide spectrum and high photoelectric response detection.It had obvious optical response in both visible and infrared light bands,of which the response degree in the infrared band was as high as 1.84 AW-1,the response time was 35 ms,and the detection rate D*was 1.50x109 cmHz1.2W-1.(3)Preparation and properties of 3D molybdenum sulfide photodetector by chemical vapor depositionThe high quality 3D molybdenum sulfide with vertical orientation was prepared by chemical vapor deposition method.firstly,the growth-mechanism of 3D molybdenum sulfide was studied,and then the photoelectric detector of 3D molybdenum sulfide was prepared.test results show that the detector has the characteristics of high sensitivity and high responsiveness.The response degree at 532 nm could reach 133 AW-1,the response time could reach 27.0 ms,and the specific detection rate(D*)was 3.325×1011 cmHz1/2W-1. |
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