Preparation And Properties Study Of SnSe Nanoribbons And Heterojunction Photodetectors

In the past two decades,material science and nanotechnology have achieved rapid development.Researchers have adopted various experimental techniques to synthesize novel materials with nanostructures,such as quantum dots（QD）,nanowires（NW）,nanoribbons（NR）,and thin films.Among them,IV-VI group compounds low-dimensional SnSe nanomaterials are ideal materials for applications in the next-generation optoelectronic,photovoltaic and thermoelectric devices due to their excellent properties.However,the controllable synthesis of high-quality SnSe nanostructures is still a huge challenge that hinders their in-depth research and practical applications.In addition,the performance of SnSe based photodetectors is limited by the immaturity of the SnSe material preparation process,and their responsivity and detectivity are not yet able to meet the practical needs.Based on these problems,this paper has conducted research on the controllable synthesis of low-dimensional SnSe NRs,the preparation of photodetectors,and the structural design of p-n heterojunctions,exploring the synthesis method of high-quality SnSe NRs,the effective suppression of dark currents in SnSe NR photodetectors,and the improvement of detectivity.The specific research content is as follows:1.High-quality SnSe NRs were prepared by chemical vapor deposition.The surface morphology,crystal structure,and optical properties of the SnSe NRs were characterized by scanning electron microscopy,high-resolution transmission electron microscopy,X-ray diffraction,atomic force microscopy,energy dispersive spectroscopy,and Raman spectroscopy,etc.Subsequently,the SnSe NR photodetectors were prepared by electron beam lithography and other micro-nano processing techniques.The photoelectric performance of the device was tested and analyzed.The results show that the grown SnSe NRs have a good single-crystal structure,and the SnSe NR field-effect transistors have typical p-type semiconductor properties,with a hole mobility of 2.71 cm² V^-1 s^-1.The device exhibits good photoelectric characteristics under near-infrared illumination,with a responsivity,external quantum efficiency,and detectivity as high as 376.71 A W^-1,and5.65×10⁴%and 8.66×10¹¹ Jones,respectively.The device has a fast response rise time and fall time of 43μs and 57μs.The detection range of the device can range from UV to NIR wavelengths,enabling broad-spectrum detection.These results indicate that SnSe nanoribbons have good application potential for fast response broad-spectrum photodetectors.2.A SnSe/MoS₂ heterojunction photodetector was constructed by combining p-type SnSe NRs with n-type MoS₂ two-dimensional layered materials using a fixed-point transfer platform and micro-nano processing techniques.The effective suppression and regulation of dark current is achieved by the p-n junction barrier of the device and the effect of the built-in electric field,which reduces the dark current of the device and improves the detectivity.The results show that the SnSe/MoS₂ heterojunction photodetector has a photoresponsivity of up to 2.8×10³ A W^-1,a photoconductivity gain of 5×10³,and a detectivity of up to 3.87×10¹⁴ Jones,which is hundreds of times higher than that of the SnSe NR device.The devices also have fast response rise and fall times of 51.6μs and 68.1μs,respectively.The construction of this p-n junction can significantly improve the problem of excessive dark current in p-type SnSe NR devices,which can effectively suppress the dark current and greatly improve the detectivity of the devices without significantly reducing the response speed of the devices.This work indicates that SnSe/MoS₂ heterojunction photodetectors can effectively suppress the dark current and improve the detectivity,which provides a good idea for the application of p-type semiconductor nanomaterials in high-performance photodetectors.