Research On Photodetector Based On Molybdenum Disulfide Heterojunction

In the field of photoelectric detection,two-dimensional transition metal sulfide materials have the advantages of high switching ratio and high carrier mobility,but their absorption bands are narrow,and currently they are not possible to prepare high-quality two-dimensional materials in large quantities in industry.Compared with inorganic two-dimensional materials,organic materials have a wider light absorption spectrum and are simple to prepare.In addition,organic materials can modify different electrical and optical properties by modifying various functional groups.The combination with inorganic two-dimensional materials to form heterojunctions can significantly improve the functionality of the device.In addition,there are usually a large number of conjugated?bonds in the molecular structure of organic conductive polymers,which makes it possible to form a two-dimensional interface similar to an inorganic van der Waals heterojunction through the interaction between van der Waals and molybdenum disulfide.On the surface of the two-dimensional material,an ordered molecular structure is formed,and an organic-inorganic van der Waals heterojunction is formed between the organic molecule and the two-dimensional inorganic material using Van der Waals forces.In this paper,the preparation and characterization of molybdenum disulfide-based photodetectors are studied,and organic and organic/graphene structures are combined with molybdenum disulfide to form Van der Waals heterojunction photodetectors.The devices are mainly prepared by mechanical stripping methods,ultraviolet lithography,electron beam lithography,thermal evaporation coating,plasma etching,wet transfer graphene,and dry transfer molybdenum disulfide.The main research results of device performance are as follows:?1?The cut-off wavelength of molybdenum disulfide in the molybdenum disulfide-organic semiconductor heterojunction photodetector is around 808 nanometers,and the lead phthalocyanine film has absorption from 400 to 1000 nanometers,but the absorption is very weak in the green light band.The MoS₂-PbPC heterojunction device has a response in the visible to near-infrared band,which is mainly due to the complementary absorption of the two materials.The presence of lead phthalocyanine broadens the device's response band.The average photogenerated current of the device is on the order of nanoamperes,the highest responsivity is 6.5 A/W,and the response time is 243.5 ms.The resistance of the device is on the order of T?,which shows that our device is mainly limited by the lateral transmission channel of PbPC.Heterojunctions composed of different organics and molybdenum disulfide have significantly different response bands.Finally,the CuPC-MoS₂ device is used as the object to study the effect of gate voltage on device performance.This has great inspiration for the functionalization of MoS₂-based heterojunction detectors.?2?g-p-n type heterojunction photodetector.The composition of the device is graphene/lead phthalocyanine-molybdenum disulfide.The electrical characteristics of the device were tested.The open circuit voltage and short-circuit current of the device were studied under dark and light conditions.The photodetection performance of the device was tested.The device's responsivity was 31.1 A/W,and the specific detection rate was up to 3.21×10¹² Jones in photovoltaic operation mode,and working in photoconductive mode,the external quantum efficiency can reach 95.23.The relationship between the photocurrent,responsivity,specific detection rate,external quantum efficiency,and bias voltage and optical power was also studied.It is proved that the responsivity,the external quantum efficiency is proportional to the magnitude of the bias voltage,and is inversely proportional to the optical power.The magnitude of the photocurrent is proportional to the magnitude of the bias voltage and the optical power.The device has a response in the visible light band to the near-infrared band.Among them,the response current is large between 405 nm and 980 nm,which is derived from the strong light absorption of MoS₂and PbPC in this band.At 1310 nm and 1550 nm,it is mainly derived from graphene.Absorption.The response time of the device is 78.35 ms.Compared with MoS₂-PbPC heterojunction devices,the participation of graphene has greatly improved the device's responsiveness,quantum efficiency,and response time,which provides a reference for functionalized molybdenum disulfide-based photodetectors.