| As a carrier of information transmission,photoelectric detector can transform optical signals into electrical signals and it has a wide range of applications in the fields of national defense,military,communication and industry.In recent years,people have put forward higher demand for photoelectric detector,which can not be satisfied by traditional photoelectric detector.Under this background,two-dimensional materials emerge and provide a new direction for the development of photodetector.Graphene is the first material with two-dimensional layered structure discovered,however,the zero-band gap of graphene limits its development potential in the field of photoelectric detection.Therefore,two-dimensional transition metal chalcogenides(2D TMDCs)with adjustable band gap have attracted wide attention of researchers because of their excellent photoelectric,mechanical and flexible properties,and have been used in many fields such as imaging,communications,national defense and night vision.The preparation of large-size and high-quality 2D TMDCs films has become an important prerequisite for its practical application.Therefore,the preparation process of MoSe2 and MoS2 was studied in this paper.The specific research contents are as follows.Firstly,the Controllable preparation of high quality MoSe2 thin films was studied.In this paper,chemical vapor deposition(CVD)was used to explore the growth mechanism of MoSe2 thin films.The key factors affecting the film growth were studied and the micromorphology of the MoS2 films under different preparation process conditions was studied.Monolayer MoS2 films were obtained by optimizing the preparation process parameters.The influence mechanism of NaCl catalyst and H2 atmosphere on the growth of MoS2 thin films was studied.MoS2 thin films with different single crystal size and layer thickness were prepared by adjusting the content of NaCl and H2.The monolayer and homogeneity of MoS2 thin films were proved by Raman spectroscopy and atomic force microscopy.The results of this study are of great significance for the preparation of large size and high quality continuous MoS2 films.Secondly,the Controllable preparation of monolayer and large size single crystal MoS2 thin films was studied.Based on the results of MoSe2 thin film preparation,the controllable preparation of MoS2 thin film was studied.The effects of reaction temperature,reaction time and carrier gas flow rate on the growth of MoS2 thin films were studied,and the growth mechanism of MoS2 thin films was discussed and analyzed.The internal relations between the growth of the films and the reaction temperature,reaction time and carrier gas flow rate were revealed.In addition,the promotion effect of NaCl catalyst on the growth of MoS2 thin films was also explored.Monolayer and large-size MoS2 films were prepared by optimizing the content of NaCl.The results lay a foundation for the preparation of large-scale continuous films.At the same time,it is also verified that these factors are common to the preparation of other TMDCs,which laid afoundation for the follow-up study of the preparation process of other 2D TMDCs.Finally,the photoelectric characteristics of MoS2 are studied.In this study,thesemiconductor preparation process was used to deposit Cr/Au on Si/SiO2 substrate with a single layer of MoS2 thin film to test the photoelectric characteristics of MoS2,and the response range,response time and detection rate of the material were mainly explored.The experimental results show that the monolayer MoS2 thin films prepared by CVD are responsive in the spectral range of 532nm ? 980nm.When the light source wavelength is 532nm and the source drain bias voltage is 2V,the rise time of the device is 60ms,the fall time is 140ms,the optical responsivity is 1.03AW-1,and the detectivity is 6.68×109jones. |
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