Monolayer WS_2xSe_2-2x By Chemical Vapor Deposition

Currently,class graphene transition group chalcogenide caused extensive studies of human interest.Two-dimensional material MoS₂,WS₂,MoSe₂,WSe₂ etc have layers dependent band gap structure,transition group chalcogenide band gap can be regulated,about 0.8 2.1eV,because they exhibit bipolar electron transport properties,become important in the future to get the application in electronics,optoelectronics device context.These materials are potentially highly sensitive optical and electrical properties,but subject to different adsorption properties of single atomic layer thickness and a different band gaps different spectral selectivity.Our two-temperature zone by chemical vapor deposition system he has built himself,on Si/SiO2 substrates grown WS₂,WSe₂,WS_2xSe_2-2x（0 <x <1）film.By changing the growth conditions and raw materials,you can get different S,Se ratio（n-type or p-type doped p-doped n）doped film sample,after completion of growth,the resulting sample size and morphology can be observed by an optical microscope,the use of layers and surface roughness AFM sample can be determined,offset can also be observed by a transmission arrangement to the sample preparation flatness atoms,followed by Raman spectroscopy to obtain samples doped with different single characteristic Raman peaks,roughly seen S,Se different amounts of doping by PL spectrum peaks can be calculated S,the doping amount of Se.Three intermediate doped sample selection gradient,respectively,x = 0.25,0.5,0.75.The sample size was chosen 20mm,the current ratio of the switch FETs 104 is prepared,the electron mobility of the n-type WS₂ was 3,p-type WSe₂ was 12cm2/Vs,n-type to p-type transition voltage from a positive to a negative voltage voltage mobile.By giving different wavelengths of laser irradiation device,the ratio of different samples doped response time varies,quantum dots after dropping the device response time than previous increases.