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Optical Properties of Layered Semico...

Wei, Guohua.

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Optical Properties of Layered Semiconductor Nanostructures.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Optical Properties of Layered Semiconductor Nanostructures./
Author:	Wei, Guohua.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
Description:	216 p.
Notes:	Source: Dissertation Abstracts International, Volume: 79-02(E), Section: B.
Contained By:	Dissertation Abstracts International79-02B(E).
Subject:	Condensed matter physics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10288969
ISBN:	9780355295467

Optical Properties of Layered Semiconductor Nanostructures.
Wei, Guohua.

Optical Properties of Layered Semiconductor Nanostructures. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 216 p.

Source: Dissertation Abstracts International, Volume: 79-02(E), Section: B.

Thesis (Ph.D.)--Northwestern University, 2017.

This item is not available from ProQuest Dissertations & Theses.

Optical properties of layered semiconductor nanostructures, from nanodots to nanoribbons, are studied in this thesis. Group-VI transition metal dichalcogenides (TMDs) are a class of van der Waals layered semiconductors that possess exotic electronic and optical properties at an atomic thickness. In particular, monolayer TMDs are direct bandgap semiconductors that host excitons with rich spin and valley physics. In this thesis, a high-resolution nanopatterning process utilizing electron beam lithography techniques is developed for creating nanodots and nanoribbons of 2D monolayer semiconductors with size-tunable optical properties. Valley polarization in monolayer MoS2 is measured not to be modified by quantum confinement down to a size scale of 15 nm, consistent with theoretical prediction. The nanofabrication technique enables the study of the valley dynamics for the first time in a quantum confinement regime. Size-tunable photoluminescence of monolayer semiconductor nanodots and nanoribbons are demonstrated and non-equilibrium models are successfully applied to explain the size-dependent exciton energy shift. Exciton temperature dynamics are investigated in the quantum confinement regime that show reduced phonon scattering. Anisotropic Raman scattering is quantitatively studied by polarization resolved Raman spectroscopy in monolayer MoS2 nanoribbons, and size effects on Raman intensity, frequency shift and linewidth broadening are investigated. In addition, optical studies on few-layer ReS2 nanodots reveal weaker exciton binding of the linearly polarized excitons and stronger confinement effects than that observed in molybdenum or tungsten TMDs. Coupling of 2D semiconductors with optical cavities that host nontransverse photons, potentially useful for valley-sensitive quantum devices, is investigated, and the coupling in classical regime is implemented experimentally. Optical studies of the 2D semiconductor nanostructures provides a deeper understanding of the effects of and on defect states, excitons and valleys of layered semiconductors. The ability to create nanodots and nanoribbons with a CMOS compatible process paves the way for integrated photonic quantum devices with valley sensitivity, and spintronic applications of nanoribbons in quantum spin Hall insulator phase.

ISBN: 9780355295467Subjects--Topical Terms:

3173567
Condensed matter physics.

Optical Properties of Layered Semiconductor Nanostructures.
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500 $a Source: Dissertation Abstracts International, Volume: 79-02(E), Section: B.
500 $a Adviser: Nathaniel P. Stern.
502 $a Thesis (Ph.D.)--Northwestern University, 2017.
506 $a This item is not available from ProQuest Dissertations & Theses.
520 $a Optical properties of layered semiconductor nanostructures, from nanodots to nanoribbons, are studied in this thesis. Group-VI transition metal dichalcogenides (TMDs) are a class of van der Waals layered semiconductors that possess exotic electronic and optical properties at an atomic thickness. In particular, monolayer TMDs are direct bandgap semiconductors that host excitons with rich spin and valley physics. In this thesis, a high-resolution nanopatterning process utilizing electron beam lithography techniques is developed for creating nanodots and nanoribbons of 2D monolayer semiconductors with size-tunable optical properties. Valley polarization in monolayer MoS2 is measured not to be modified by quantum confinement down to a size scale of 15 nm, consistent with theoretical prediction. The nanofabrication technique enables the study of the valley dynamics for the first time in a quantum confinement regime. Size-tunable photoluminescence of monolayer semiconductor nanodots and nanoribbons are demonstrated and non-equilibrium models are successfully applied to explain the size-dependent exciton energy shift. Exciton temperature dynamics are investigated in the quantum confinement regime that show reduced phonon scattering. Anisotropic Raman scattering is quantitatively studied by polarization resolved Raman spectroscopy in monolayer MoS2 nanoribbons, and size effects on Raman intensity, frequency shift and linewidth broadening are investigated. In addition, optical studies on few-layer ReS2 nanodots reveal weaker exciton binding of the linearly polarized excitons and stronger confinement effects than that observed in molybdenum or tungsten TMDs. Coupling of 2D semiconductors with optical cavities that host nontransverse photons, potentially useful for valley-sensitive quantum devices, is investigated, and the coupling in classical regime is implemented experimentally. Optical studies of the 2D semiconductor nanostructures provides a deeper understanding of the effects of and on defect states, excitons and valleys of layered semiconductors. The ability to create nanodots and nanoribbons with a CMOS compatible process paves the way for integrated photonic quantum devices with valley sensitivity, and spintronic applications of nanoribbons in quantum spin Hall insulator phase.
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