| Two-dimensional transition metal dichalcogenides（TMDs）have attracted much attention due to their unique structure and excellent photoelectric performance.A variety of band gap is essential in the field of optoelectronics.However,the band gap types of TMDs materials are limited.Therefore,the band gap engineering of TMDs has become one of study hotspots.The alloying of TMDs can regulate the band gap of the material and achieve the purpose of enriching the band gap of TMDs.In this paper,NaCl-assisted CVD is investigated to obtain the controllable synthesis of monolayer MoS2,and monolayer MoS2xSe2（1-x） alloy with adjustable band gap was synthesized on the basis of preparing MoS2.The specific studies are as follows:（1）By studying the effects of the growth temperature:the amount of reactant,the type of substrate and the amount of NaCl on the growth of monolayer MoS2 crystals,the optimal growth conditions for the preparation of monolayer MoS2 were obtained.Furthermore,the samples prepared under the optimal growth conditions were characterized by optical microscope,Raman spectrum and so on.The results show that the samples are monolayer MoS2.The size of a single MoS2 crystal on the molten glass substrate can be up to 400μm,and the continuous film size of MoS2 made on Si/SiO2 substrate can reach the millimeter level.（2）Monolayer MoS2xSe2（1-x） alloy was successfully prepared by introducing Se source on the basis of preparing MoS2 by NaCl-assisted CVD method.The results revealed that monolayer MoS2xSe2（1-x） alloy with sizes reaching 100μm can be synthesized.Atomically thin uniform MoS2xSe2（1-x） alloy have been synthesized with band gap tunability by adjusting the amount of S source and Se source in the reaction system.The test results of PL revealed that all samples show a single emission peak,with the spectral peak position shifting from 669 nm to 810 nm.That is,the band gap adjustment range of the alloy is 1.50 eV～1.85 eVFigure 36,table 2,references 69. |
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