Research On The Construction Of Low Dimensional Heterogenous Junction And Its Photoelectric Detection Performance Based On WSe₂

Two dimensional（2D）transition metal chalcogenides（TMDs）.The band gap（1～2 e V）varies with the number of layers,the width of the band gap will gradually increase due to the coupling effect between layers and quantum confinement effect when the thickness of the material decreases from bulk material to atomic layer,thus changing the detection range of the spectrum.It has become the material system in the application field of new optoelectronic devices.WSe2 is a typical transition metal disulfide.Heterojunction devices based on WSe2 Two-Dimensional materials have important applications.The space charge region at the interface between two materials can improve the separation efficiency of photogenerated carriers and the comprehensive performance of photodetectors.On the other hand,a single WSe2 Two-Dimensional material has a high light absorption rate,but it has a low light absorption due to its two-dimensional structure.This study focuses on the optimization of the photoelectric properties of WSe2 two-dimensional materials from three aspects:（1）Fabrication of WSe2 field effect transistor（FET）and its photoelectric detection performance research:In this study,a few layers of high quality WSe2 samples were separated from WSe2 bulk materials by mechanical stripping.The stripped two-dimensional material was transferred to Au electrode to prepare field effect transistor（FET）and explore its photoelectric performance.The single WSe2 material has good electrical properties and the carrier mobility is3.42 cm²/V·s.However,the photoelectric detection responsivity is only 0.61 A/W and the response time is 145μs/139μs.（2）WSe2/MoS2 heterostructure preparation and photoelectric detection performance research:Based on the traditional WSe2/MoS2 heterostructure,we designed to control the concentration of S vapor by adjusting the heating time of the low temperature region（S source）in the double temperature region tube furnace in the CVD growth process,so as to realize the preparation of MoS2 two-dimensional materials with low S vacancy defects.The MoS2 samples with high crystalline quality were transferred to the Si O2 substrate bonded with WSe2 samples by wet transfer technology,and the p-n heterojunction interface with high crystalline quality was obtained.The results show that the responsivity of WSe2/MoS2heterojunction is 41.15 A/W（67 times of single WSe2 photodetector）,and the response time is 102μs/110μs（2.7 times of single WSe₂ photodetector）.（3）Fabrication of WSe2/ZnO QDs heterostructure and its photoelectric detection performance research:The 2D/0D heterostructure photodetector made of ZnO QDs and WSe2 two-dimensional materials is used for the first time.We prepared ZnO QDs with larger specific surface area and spin coated them on the surface of WSe2 two-dimensional materials,which effectively solved the problem of insufficient light absorption of WSe2two-dimensional materials in two-dimensional scale.The results show that the device can effectively reduce the dark current and broaden the detection range（350-800 nm）.The response of WSe2/ZnO QDs heterostructure is 16.2 A/W（26 times of single WSe2photodetector）,and the response time is 46μs/42μs（3 times of single WSe₂ photodetector）.