| WS2 has attracted the attention of researchers in recent years due to its excellent photoelectric properties.It has good ductility,soft,transparent characteristics and high carrier mobility.At the same time,it has a band gap,which can provide a lower cut-off current and a higher switching ratio.WS2 crystal film has broad development prospects in field effect transistors,photodetectors,gas sensors and other fields.However,the controllable equipment and device construction of WS2 crystal film were still in its infancy.In this paper,the technology of preparing monolayer WS2 crystal thin film by Chemical vapor deposition(CVD)was studied,and the technology of preparing WS2 photodetector based on SiO2/Si and PI substrate by different transfer methods was studied.The photoelectric characteristics of WS2 photodetector and the effects of low temperature annealing and curing,oxygen plasma treatment and spin coating g-C3N4 on the performance of WS2 photodetector have been studied.The main research results have been obtained:(1)The influence of growth process on WS2 crystal film was revealed.The reaction temperature,S introduction time,gas flow rate,and the distance between the growth substrate and the tungsten source were studied in detail,and the optimal preparation conditions were obtained.The reaction temperature is 910℃,the maximum heating temperature of S element is 250℃,the S introduction time is 3 min,the holding time is 15 min,the amount of precursor WO3 and S are 0.02 g and 0.8 g respectively,the gas flow rate is 90 sccm,and the growth substrate is sapphire Substrate,the distance between the growth substrate and the tungsten source is 11 cm.A high-quality WS2 crystal film with good morphology was prepared in the conditions.(2)The preparation process of single-layer WS2 crystal thin-film photodetectors based on SiO2/Si and PI substrates was studied,and the influence of light intensity,external field bias and wavelength on the photoelectric performance of the device was clarified.It is found that the photoelectric performance decreases with the increase of light intensity;the photoelectric performance of the WS2 photodetector increases with the increase of the bias voltage;the photoelectric performance of the WS2 photodetector increases with the incident.As the wavelength of light increases,the photoelectric performance of the device decreases.Among them,the photoresponse of the WS2 photodetector based on SiO2/Si substrate is the highest 0.307 A/W,and the rise and decay times are 58 ms and 446 ms,respectively.The photoresponse of the WS2 photodetector based on the PI substrate is up to 0.026 A/W,and the rise and decay times are 44 ms and 37 ms,respectively.(3)It is found that low temperature annealing and curing treatment,oxygen plasma treatment and g-C3N4 treatment can improve the photoelectric performance of WS2 photodetector.The photoelectric properties of the device can be improved by annealing and curing.The optimal annealing temperature is 150℃ and curing time is 5 min.Oxygen plasma treatment can greatly improve the optoelectronic performance of the device.After treatment,the optical responsiveness can reach up to 52.4A/W.g-C3N4 can improve the photoelectric performance of near-ultraviolet devices. |
