Study On The Configuration And Properties Of Self-driven Photodetectors Based On Twodimensional InSe And WS₂

Photodetectors play a very important role in medical imaging,biological detection,wearable devices,optical communication,industrial automation production,military and national defense and many other fields.With the rapid development of science and technology,photodetectors are developing in the directions of miniaturization,wide band,fast response,and low power consumption.Traditional photodetector thin film materials have gradually failed to meet people’s requirements for new high-performance photodetectors.Since the discovery of graphene,two-dimensional materials have provided new ideas for the breakthrough of traditional light detectors due to their unique physical properties.Two-dimensional materials with tunable band gaps,dangling bond-free surfaces and strong mechanical flexibility have great potential in the development of new high-performance photodetectors,which are expected to be applied in the biomedical field.At present,many two-dimensional semiconductor photodetectors have been reported,but there is still a long distance between them and the practical application,and there are still many problems,such as low response,slow response speed,complex preparation technology,etc.In view of the above prominent problems existing in the two-dimensional material photodetector,this paper carried out the design and working mechanism research of the self-driven photodetector based on two-dimensional InSe and WS₂,which lays the foundation for the realization of photodetector technology with fast response,high signal-to-noise ratio,and wide band response.The main research contents of this paper are as follows:1.In order to obtain the high performance self-driven photodetector of two-dimensional Schottky junction,the Au-InSe-Au Schottky junction self-driven photodetector was constructed,and its working mechanism and influencing factors were investigated.Au-InSe-Au devices were fabricated by mechanical stripping and dry transfer techniques.The working mechanism and influencing factors of the devices were systematically investigated by means of Kelvin probe atomic force microscopy test,band arrangement and carrier transport analysis.The results show that the different heights of the two ends of the Au-InSe Schottky barrier and the difference of the Au-InSe contact geometry（including the length of the contact edge,the contact area,and the thickness of the InSe nanosheet）promote and influence the realization of the self-driven photoelectric detection of the device.Under 0 bias voltage,the device achieved A responsivity of 0.103 A/W,a detection rate of 1.83×10¹⁰ Jones,a photocurrent switching ratio of 10⁴,a fast response speed of 1 ms,and a wide optical response of 300-1000 nm.2.On the basis of the successful construction of Au-InSe-Au Schottky junction self-driven photodetector,the Au-WS₂-Au Schottky junction self-driven photodetector was constructed.At the same time,R6G organic molecules were modified to form a composite structure of WS₂and R6G,which improved the optical response of the device.Photoluminescence and time-resolved photoluminescence spectroscopy were used to explore the charge transfer kinetics at the heterogeneous interface of WS₂ and R6G composite structure,in order to reveal the physical mechanism of R6G organic molecules improving the photoresponse of the device.The analysis results show that WS₂ and R6G form a heterogeneous interface with type Ⅱ band arrangement,which promotes the separation of photogenerated electron-hole pairs,thereby improving the photoelectric response of the device.3.A WS₂/InSe van der Waals heterojunction device was constructed using mechanical stripping and dry transfer techniques to realize fast response and wide band self-actuated photoelectric detection.The photovoltaic effect of heterojunction was used to explore the optical response performance,including response speed,response,detection rate,light-dark current ratio,and wavelength response characteristics.The Fermi energy level difference between WS₂ and InSe was tested by Kelvin probe atomic force microscope,and the working mechanism of the device was analyzed by energy-band alignment.The device achieved an open circuit voltage of 0.47 V and a short circuit current of 11.7 nA.At zero bias,it exhibited fast response time（rising/falling time of 63/76μs）,high light-dark current ratio（10⁵）,and high detection rate(2.5×10¹¹ Jones),and wide band photoresponse（325-980 nm）.The excellent performance of the devices is attributed to the unique photoelectric properties of InSe and WS₂ and the presence of strong built-in electric fields in their heterojunctions,which promote the rapid carrier separation.