Fabrication And Properties Of Two-dimensional WS₂ Van Der Waals Heterojunction Optoelectronic Devices

The structural and electronic diversity of van der Waals（vdW）bonded layered materials opens up new avenues for basic scientific research and device application design.In fact,any passivated,non-dangling bond surface can interact with another surface through the vdW force.Therefore,we can not only stack these materials together in a controlled manner,but also extend to the combination of two-dimensional materials and non-two-dimensional materials,which provides a promising method for designing and manufacturing new electronic devices.In this paper,based on one-dimensional GaSb nanowires,two-dimensional ASP films and WS₂ materials with excellent properties,their physical properties are studied respectively,and mixed and full two-dimensional heterojunctions are constructed to further explore their properties from optoelectronics.The main research contents are as follows:（1）One-dimensional GaSb nanowires were prepared by CVD method and two-dimensional WS₂ nanosheets were prepared by mechanical exfoliation method.Through the characterization of two materials including:OM,AFM,KPFM,Raman,SEM,etc.,the microstructure,morphology,and physical properties of the material were studied;the GaSb/WS₂ mixed-dimensional heterojunction was prepared using a dry transfer platform,and the heterojunction was further characterized,verifying that it has a higher quality and a cleaner contact interface,laying a solid foundation for follow-up performance research.（2）The above materials and heterojunctions were used to fabricate field-effect transistors through micro-nano processing,and the electrical properties of individual materials and heterojunctions were tested.First,we proved that GaSb and WS₂ are p-type and n-type semiconductors with excellent performance.Then the performance of the heterojunction is tested,and the heterojunction has a high rectification ratio of 10⁴ when used as a diode.When the heterojunction is used as a JFET,it also shows excellent transfer characteristics,with ON/OFF about 10⁶,and the sub-threshold swing（SS）is limited to 166 mV dec^-1,the cut-off voltage is 1.5 V,and the ultra-high carrier mobility rate is about 318.5 cm²V^-1s^-1.In addition,JFET shows good stability at high temperature,which proves that it has unlimited application prospects as a low-power device.（3）In this paper,a full two-dimensional heterojunction was also made.The AsP and WS₂ nanosheets obtained by mechanical exfoliation were used to prepare the WS₂/AsP heterojunction,and the heterojunction was characterized and photoelectric performance test.The results show that the WS₂/AsP heterojunction has a rectifying effect,and the ideality factor is 1.67.In terms of photodetection,when the power is 11.23 nW and the bias voltage is-3 V,the maximum response rate of the heterojunction is 0.02 A/W.Analysis of the response time shows that the rise time is about 0.31 s and the fall time is about 0.16 s.