Preparation And Photoelectric Characteristics Of Two-dimensional Material Heterostructure

In recent years,two-dimensional materials have gradually grab researchers'eye for their atomic-level thickness and dangling-free chemical bonds.Unlike their corresponding bulk counterpart,2D materials exhibit a series of distinguished photoelectric properties,so they are widely applied in high-performance field effect transistors,photoelectric sensors and other electronic devices.Also,due to the weak interlayer van der Waals(vd W)forces,different 2D materials can be easily combined together to form heterostructure.However,these devices still have some shortcomings.For example,the rough surface layer of the non-vd W gate oxide layer hinders the movement of carriers,resulting in lower mobility;and the 2D materials are likely to be destroyed by the corrosion liquid when using the photolithography processes during device fabrication.In response to the above problems,a full vd W heterostructure photodetector and the device structure were designed and realized by a mechanical exfoliating and transferring method.This structure can effectively reduce the damage of materials and interfaces,and achieve a higher photodetector performance.The main results are as follows:1.Few layer high-quality two-dimensional materials such as graphene,hexagonal boron nitride,mica,and molybdenum disulfide were prepared by the improved mechanical exfoliation method.The morphology,structure and composition of these materials were characterized by using AFM,Raman,SEM and other methods.The results showed that we have successfully prepared large-area,high-quality 2D materials with few layers.2.Molybdenum disulfide,mica and graphene were used to construct photodetectors,the photoelectric characteristics of the device were measured.The results show that the carrier mobility of the detector reached 63.4cm²/Vs,and the switching current ratio was as high as 10⁷.The responsivity and detectivity of our device reached 331.7A/W and 4.4×10^Jones when applied 532nm laser with intensity of 400?w/cm².3.Tin disulfide,hexagonal boron nitride and graphene were used to construct fully vd W heterostructure devices.The devices were characterized and measured with different methods.The results shown that the device had high carrier mobility of 112cm²/Vs,and under low light intensity(?50nw/cm²)condition at three different wavelengths(405 nm,450 nm and 532 nm).The responsivity and normalized detectivity of the device exceeded 10⁶A/W and 10¹³Jones respectively,which are superior to the published experiment data of the SnS₂ photodetectors.4.Black phosphorus,boron nitride,and graphene were stacked together to form heterostructure photodetectors and their electrical properties were initially measured.It was found that the black phosphorus was severely degradated in the air.Therefore,the degradation process and the effect of the destroyed black phosphorus on the device were studied.