Raman Spectroscopy Analysis Of The Novel Two-dimensional Material MoS_2（1-x）Se_2x And Research On Its Phototransistor Performanc

Two-dimensional materials refer to layered materials with a thickness of only nanometers.Since electrons can only move freely in a two-dimensional plane,they usually have peculiar carrier migration and thermodynamic diffusion properties,greatly promoted the development and progress in the field of materials,bring more high-quality choices to many fields such as electronics,biology,aerospace,etc.Mo S₂,as a representative of two-dimensional transition metal dichalcogenides,the single layer has a band structure with a direct band gap,which makes up for the disadvantage that graphene has no band gap,and has great potential in the application of optoelectronic devices.On this basis,in this work,the ternary TMD alloy Mo S_2（1-x）Se_2x was synthesized by introducing Se atoms into Mo S₂ through specific process,which not only retains its original advantages,but also has the advantage of tunable band gap.Accordingly,the structural characteristics of Mo S_2（1-x）Se_2x were systematically analyzed by means of Raman spectroscopy,fills the theoretical research gap of ternary TMD materials.At the same time,the development of a new two-dimensional material Mo S_2（1-x）Se_2x transistor is expected to further improve the performance of phototransistors.We synthesized the MoS_2（1-x）Se_2x sample by chemical solution deposition method,and characterized its molecular structure,band gap,Se element content,thickness and other important physical information by Raman spectra,Photoluminescence spectroscopy,X-ray photoelectron spectroscopy and Atomic Force Microscope.The structural changes of single-layer and multi-layer are analyzed,including the changes in Raman spectra of disorder introduced by doping impurities,and the lattice changes at grain boundaries.The method of judging the number of layers by Raman displacement difference is verified,and the relationship between the content of Se and the ratio of Raman characteristic peaks is produced.Finally,the performance of the phototransistor based on the monolayer Mo S_2（1-x）Se_2x sample was measured,including its responsivity and detectivity at different power densities,and its dynamic switching characteristics under 405-nm laser illumination with a power density of 60 m W/cm².Under the condition of 405-nm laser illumination with a power density of 112.1μW/cm² and 0.5 V bias voltage,the sample exhibited the maximum responsivity of 28.8 A/W,the detectivity up to4*10¹⁰ Jones.Under the condition of 2 V bias,0 V gate voltage,405 nm wavelength and 60m W/cm² illumination,the on-off ratio is up to 10²,the rise time is 2.6s,and the fall time is 5.6s,showing the excellent potential of Mo S_2（1-x）Se_2x sample in optoelectronic devices,providing more choices for application and scientific research.