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Mildred S. Dresselhaus. Lin, Yuxuan, Ph. D. Massachusetts Institute of Technology Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science 2015-01-20T17:58:48Z 2015-01-20T17:58:48Z 2014 2014 http://hdl.handle.net/1721.1/93059 899994570 Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014. Cataloged from PDF version of thesis. Includes bibliographical references (pages 91-115). The re-discovery of the atomically thin transition metal dichalcogenides (TMDs), which are mostly semiconductors with a wide range of band gaps, has diversified the family of two-dimensional materials and boosted the research on their potential applications in the fields of logic nanoelectronics and high-performance nanophotonics. Many body effects are of great significance in 2-dimensional TMDs, especially when thinned down to a monolayer. As a result, the exciton-related phenomena are prominent in TMD monolayers, which distinguish the monolayers significantly from their bulk counterparts. This thesis systematically studies the optical properties in semiconducting, monolayer TMDs, including Raman spectroscopy, photoluminescence (PL), and optical absorption. In order to further understand the excitononic properties in 2-dimensional TMDs, we took monolayer MoS2 as an example, and studied its exciton behaviors with different carrier densities and dielectric environments through PL measurements with the help of electrochemical gating and non-ionic solvent immersion. Our findings are helpful to understand better the tightly bound excitons in low-dimensional systems and to provide a simple approach to controlling the generation of excitons and trions (charged excitons) selectively and separately. by Yuxuan Lin. S.M. 115 pages eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Electrical Engineering and Computer Science. Optical properties of two-dimensional transition metal dichalcogenides Optical properties of two-dimensional TMDs Optical properties of 2-dimensional transition metal dichalcogenides Optical properties of 2D transition metal dichalcogenides Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="810c3cf2-9ad0-4797-b0d1-eefdd9d769e3"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Optical properties of two-dimensional transition metal dichalcogenides</Title> <Subtitle>Optical properties of two-dimensional TMDs</Subtitle> <Subtitle>Optical properties of 2-dimensional transition metal dichalcogenides</Subtitle> <Subtitle>Optical properties of 2D transition metal dichalcogenides</Subtitle> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2014</PublicationDate> <Authors> <Author> <DisplayName>Lin, Yuxuan, Ph. D. Massachusetts Institute of Technology</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Electrical Engineering and Computer Science.</Keyword> <Abstract>The re-discovery of the atomically thin transition metal dichalcogenides (TMDs), which are mostly semiconductors with a wide range of band gaps, has diversified the family of two-dimensional materials and boosted the research on their potential applications in the fields of logic nanoelectronics and high-performance nanophotonics. Many body effects are of great significance in 2-dimensional TMDs, especially when thinned down to a monolayer. As a result, the exciton-related phenomena are prominent in TMD monolayers, which distinguish the monolayers significantly from their bulk counterparts. This thesis systematically studies the optical properties in semiconducting, monolayer TMDs, including Raman spectroscopy, photoluminescence (PL), and optical absorption. In order to further understand the excitononic properties in 2-dimensional TMDs, we took monolayer MoS2 as an example, and studied its exciton behaviors with different carrier densities and dielectric environments through PL measurements with the help of electrochemical gating and non-ionic solvent immersion. Our findings are helpful to understand better the tightly bound excitons in low-dimensional systems and to provide a simple approach to controlling the generation of excitons and trions (charged excitons) selectively and separately.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>