Preparation And Properties Of GaSe/MoS₂ Photoelectric Heterojunction

With excellent mechanical properties,lubrication properties,catalytic properties and photoelectric properties,MoS₂ has a wide range of applications in the fields of machinery,chemical engineering and photodetection.In terms of photoelectric performance,since single-layer MoS₂ has a direct band gap of 1.8 to 1.9 eV,it has been widely concerned.However,the preparation and morphology control of single-layer MoS₂ and the improvement of the performance of MoS₂ two-dimensional device have always been difficult problems.For the preparation of single-layer MoS₂,based on the comparative literature,a single layer of MoS₂ was obtained by chemical vapor deposition in a vacuum tube furnace using MoO₃ and sulfur powder as raw materials.In the morphology control study of MoS₂,MoS₂ of planar polygonal structure and longitudinal annular structure were obtained by adjusting the growth time and position.Scanning electron microscopy（SEM）,atomic force microscopy（AFM）and Raman spectroscopy（Raman）were used to characterize the different morphology of MoS₂.Besides,the lateral and vertical growth modes of MoS₂ were studied to control the morphology of MoS₂.Based on the single-layer MoS₂ obtained by chemical vapor deposition,the MoS₂two-dimensional device was successfully fabricated by photolithography and evaporation.Through the test of electrical transport performance,it was found that the switch ratio of the device is relatively large,therefore,the gate voltage can be used to achieve good regulation.In the photoelectric performance study of the device,by controlling the wavelength and intensity of the excitation light,it was found that the device has the strongest response to the monochromatic light（300-400 nm）in the ultraviolet region,and the response of the device increases with the reduce of light intensity.In addition,in the case of high light intensity,the device can maintain good stability and repeatability under the continuous state of 300 seconds of light on and off,and the ratio of light-dark response is up to 3.Using a transfer platform,a GaSe/MoS₂ heterojunction was prepared by transferring a small layer of GaSe obtained by mechanical stripping onto a single layer of MoS₂,and the electrodes were all overlapped with MoS₂ to form a GaSe/MoS₂photodetector.Through the test of photoelectric performance,it was found that the response in the ultraviolet section（300-400 nm）is significantly improved,especially,the response value and the detection value are three times that of the MoS₂ device.In the stability test of the ultraviolet section（300-400 nm）,on the basis of maintaining good repeatability,the light-dark response ratio of the GaSe/MoS₂ photodetector improves by 85.6%.With the electrodes bonded to GaSe and MoS₂ in the GaSe/MoS₂ heterojunction,the P-N junction can work,and the photoelectric properties of the device were investigated.This device is a photovoltaic device that exhibits a rectifying effect under applied voltage.Under the excitation of ultraviolet light,the device exhibits a certain photovoltaic effect and can realize the photoelectric conversion.