Preparation And Optical Properties Of Tungsten Sulfide Nanostructures

Monolayer WS₂ has the advantages of ultrathin thickness,high carrier mobility,low resistivity and high switching ratio,exhibiting important application values in optoelectronic devices and valleytronics devices etc..Large area and high quality single layer film is an important prerequisite for developing WS₂ based optoelectronic devices.In this thesis,the preparation and optical properties of high quality single layer WS₂ thin films were studied.Detailed results are as follows:?1?A monolayer 2H-WS₂ triangular film with high luminescence quality was obtained by chemical vapor deposition on a SiO₂/Si substrate using a low melting point tungsten source.The full width at half maximum of the emission peak at 629.7 nm is about 18 nm?48 meV?.The WS₂ films can present uniformly luminous or only edge emitting luminescence by adjusting the ratio of the reactant sources between tungsten and sulfur.?2?The effects of sapphire and SiO₂/Si substrates on the Raman mode and luminescence position of monolayer WS₂ were investigated.It was found that two kinds of substrates have same stress on monolayer WS₂.However,blue shift occurred in the photoluminescence of the monolayer WS₂ on sapphire substrate due to the doping of different charged impurities on the substrate surface.?3?WS₂/Au composite was prepared by sputtering method.Comparative analysis of optical properties of monolayer WS₂ and WS₂/Au composite indicating that deposition of Au particles directly onto monolayer WS₂ leads to luminescence quenching,but can enhance the inter layer A1g??? Raman vibration mode.