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postgraduate thesis: Optical and electrical characterization of two-dimensional transition metal dichalcogenides

TitleOptical and electrical characterization of two-dimensional transition metal dichalcogenides
Authors
Issue Date2016
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Chen, X. [陈曦]. (2016). Optical and electrical characterization of two-dimensional transition metal dichalcogenides. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.
AbstractMonolayer transition metal dichalcogenides (TMDs), an emerging family of two-dimensional (2D) semiconductors with a direct band gap at visible and near-infrared range, have been attracting great interests for their extraordinary optical and electronic properties, such as enhanced exciton effect, valley related physics, giant spin-obit coupling and spin-valley locking. In this thesis, the optical and electrical characterization of 2D TMDs is discussed, focusing on the study of exciton binding energy and the optical control of spin-polarized photocurrents of 2D TMDs. The exciton binding energy in monolayer WS2 was measured to be 0.71eV by two-photon photoluminescence excitation (TP-PLE) spectroscopy. This was directly extracted as the difference between the single particle band gap and the optical band gap. The former was measured from the onset of interband continuum in TP-PLE spectrum, while the latter was obtained from the ground-state exciton peak measured in linear absorption and photoluminescence spectra of the same sample. Spin-polarized photocurrents were generated by circularly polarized laser and electrically detected by our well-designed spin-valve-like device. Remarkably, spin polarization of the photocurrents was shown to be manipulated by tuning photon energy of the circularly polarized excitation light with the same helicity, utilizing the valley dependent optical selection rules, the giant spin-orbit coupling and the spin-valley locking in monolayer TMDs. (208 words)
DegreeDoctor of Philosophy
SubjectChalcogenides - Optical properties
Chalcogenides - Electric properties
Transition metal compounds - Optical properties
Transition metal compounds - Electric properites
Dept/ProgramPhysics
Persistent Identifierhttp://hdl.handle.net/10722/250354
HKU Library Item IDb5846368

 

DC FieldValueLanguage
dc.contributor.authorChen, Xi-
dc.contributor.author陈曦-
dc.date.accessioned2017-12-30T15:01:04Z-
dc.date.available2017-12-30T15:01:04Z-
dc.date.issued2016-
dc.identifier.citationChen, X. [陈曦]. (2016). Optical and electrical characterization of two-dimensional transition metal dichalcogenides. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.-
dc.identifier.urihttp://hdl.handle.net/10722/250354-
dc.description.abstractMonolayer transition metal dichalcogenides (TMDs), an emerging family of two-dimensional (2D) semiconductors with a direct band gap at visible and near-infrared range, have been attracting great interests for their extraordinary optical and electronic properties, such as enhanced exciton effect, valley related physics, giant spin-obit coupling and spin-valley locking. In this thesis, the optical and electrical characterization of 2D TMDs is discussed, focusing on the study of exciton binding energy and the optical control of spin-polarized photocurrents of 2D TMDs. The exciton binding energy in monolayer WS2 was measured to be 0.71eV by two-photon photoluminescence excitation (TP-PLE) spectroscopy. This was directly extracted as the difference between the single particle band gap and the optical band gap. The former was measured from the onset of interband continuum in TP-PLE spectrum, while the latter was obtained from the ground-state exciton peak measured in linear absorption and photoluminescence spectra of the same sample. Spin-polarized photocurrents were generated by circularly polarized laser and electrically detected by our well-designed spin-valve-like device. Remarkably, spin polarization of the photocurrents was shown to be manipulated by tuning photon energy of the circularly polarized excitation light with the same helicity, utilizing the valley dependent optical selection rules, the giant spin-orbit coupling and the spin-valley locking in monolayer TMDs. (208 words) -
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.subject.lcshChalcogenides - Optical properties-
dc.subject.lcshChalcogenides - Electric properties-
dc.subject.lcshTransition metal compounds - Optical properties-
dc.subject.lcshTransition metal compounds - Electric properites-
dc.titleOptical and electrical characterization of two-dimensional transition metal dichalcogenides-
dc.typePG_Thesis-
dc.identifier.hkulb5846368-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplinePhysics-
dc.description.naturepublished_or_final_version-

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