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Preparation And Characterization Of Molybdenum Disulfide And Its Heterojunction

Posted on:2018-08-31Degree:MasterType:Thesis
Country:ChinaCandidate:X C ShaoFull Text:PDF
GTID:2371330566450942Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
In recent years,many breakthroughs have been achieved in the field of two-dimensional?2D?nanomaterials.The excellent electronic properties and high specific surface areas of TMDCs offer unlimited potential in various applications including sensing,catalysis and energy storage.In this work,molybdenum disulfide?MoS2?,a typical representative of TMDCs,is chosen as the focus of the study.We systematically study the effect of growth conditions on the preparation of MoS2 by chemical vapour deposition?CVD?.Subsequently,MoS2/WSe2 heterojunction is built through the method of mechanically assembled stacks and we carry out a series of studies on it.The main contents of this paper are divided into the following aspects:?1?MoS2 is prepared by CVD using molybdenum trioxide?MoO3?and sulfur powder as the reaction source.In the process of preparing MoS2,the main growth conditions,such as the growth temperature,the temperature of sulfur,the gas flow rate and the distance between MoO3 and the growth substrate are investigated.The results show that the changes of these growth conditions have a significant influence on the size and morphology of MoS2.In order to have a deeper understanding of MoS2,we use Raman spectroscopy,photoluminescence?PL?,transmission electron microscopy?TEM?and other techniques to characterize it.It is proved that the MoS2 in this work has good uniformity and high quality in crystal structure.?2?MoS2 grown by CVD and WSe2 prepared by mechanical cleavage are used as raw materials to build MoS2/WSe2 heterojunction.In order to investigate the effect of annealing on MoS2/WSe2 heterojunction,we use Raman spectroscopy and PL spectroscopy to characterize it.Compared with Raman spectroscopy of the sample before annealing,we find that the Raman characteristic peaks for MoS2/WSe2 heterojunction are significantly shiffing from that of the individual MoS2 and WSe2 monolayers after annealing process.Moreover,the results of PL spectroscopy show that both monolayer MoS2 and WSe2 have strong PL.However,PL signal is significantly quenched in MoS2/WSe2 heterostructure after annealing.These phenomena indicate that there are effective charge transfer and interlayer coupling in MoS2/WSe2 heterojunction.
Keywords/Search Tags:Molybdenum disulfide, Chemical vapour deposition, Molybdenum disulfide/Ungsten diselenide heterojunction, Interlayer coupling
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