Fabrication And Photoelectrical Properties Of Two-Dimentional SnS And SnS₂ Nanosheets

Two-dimensional(2D)metal chalcogenides have novel electrical,optical,magnetic,and thermal properties,which enables great potential applications in many related areas,such as ultra-thin,transparent,highly integrated optoelectronic devices.The investigation of 2D materials develops into one core aspect on exploring novel 2D materials and their unique properties,as well as promoting towards practical applications of 2D materials.This thesis systematically focuses on the growth parameters and unique properties of 2D SnS and SnS₂.The main results are divided into the following three parts:SnS,a highly anisotropic chalcogenide,has potential optical applications for polarization detection.we demonstrate a novel low-cost method to directly fabricate SnS nanoflakes on the PET substrates.Our research represents an important step toward scalable fabrication of the SnS nanoflakes,moreover,the flexible SnS photodetectors featured broadband spectral responses from 355 nm to 1550 nm.The responsivity and detectivity can approach up to 1.28×10³ AW^-1 and 3.02×10¹¹ Jones respectively under the ultraviolet laser of 355 nm.Furthermore,the device also exhibits excellent NIR photodetection with a specific responsivity of 69 AW^-1towards the 1550 nm regime.This method may pave a path for the future commercialization of flexible broadband optoelectronic devices.SnS₂,is a new type of Group-IV metal sulfide.Via optimized selection of substrates,substrate position,we have determined the experimental scheme and presented the scalable synthesis of large scale,single–crystalline,SnS₂ nanoflakes on silica substrates.Electrical transport studies revealed the n-type semiconducting transport behaviour with the room-temperature electronic mobility of about 0.024 cm²/V·s and on/off current ratio of 3×10⁵ for the SnS₂nanosheet.The corresponding individual SnS₂ nanosheet based photodetectors exhibit a good photoresponse at 405,450 and 532 nm.The optimal photoresponse values are measured under the illumination of 405 nm laser at room temperature:a high EQE about 43%,a spectral responsivity of 491 m A/W,a detectivity of 2×10⁸ Jones,and good repeatability and stability.