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Observation of coupled states in monolayer WS2 double quantum wells

Title
Observation of coupled states in monolayer WS2 double quantum wells
Translated Title
단층 WS2로 구성된 결합형 이중 양자우물 구조에서 나타나는 결합 상태 관측
Authors
Young-Jun Lee
DGIST Authors
Lee, Young-Jun; Kim, HyunMinCho, Chang-Hee
Advisor(s)
조창희
Co-Advisor(s)
HyunMin Kim
Issue Date
2020
Available Date
2020-06-23
Degree Date
2020-02
Type
Thesis
Description
2차원 물질, 전이금속 칼코겐화합물, 양자우물, 벨리트로닉스, 광발광
Abstract
Transition metal dichalcogenides have attracted enormous attention in valleytronics due to the valley-contrasting properties originated from the broken inversion symmetry and time-reversal symmetry. However, although many studies have been conducted until recently, challenges still exist for practical application owing to the limitation of the valley lifetime, depolarization lifetime caused by intervalley scattering, electron-hole coulomb exchange interaction, etc. Recently, the rapid progress in the study to suppress these effects has been made in the various systems such as heterostructure, bilayer system to reduce the spatial overlap of wavefunction. In this work, we suggest the coupled double quantum well struc-tures based on monolayer WS2 separated by hexagonal boron nitride barrier layers. From photoluminescence measurements, we observed coupled states not seen at single quantum well, which have the dependence on the twist angle between upper quantum well and lower quantum well. This can be understood by the formation of coupled states with antisymmet-ric and symmetric of wavefunctions confined in coupled double quantum wells.
Table Of Contents
Ⅰ. INTRODUCTION 1 1.1 Transition metal dichalcogenides (TMDs) 1 1.1.1 Electronic properties 2 1.1.2 Optical properties 6 1.2 Valleytronics 7 1.3 Motivation 11 Ⅱ. EXPERIMENTAL DETAILS 14 2.1 Fabrication method 14 1.1.1 The monolayer WS2 preparation 14 1.1.2 Dry transfer using polymer 15 2.2 Experimental measurement 17 Ⅲ. RESULTS AND DISCUSSION 18 Ⅳ. CONCLUSION 30 References 31
URI
http://dgist.dcollection.net/common/orgView/200000286645
http://hdl.handle.net/20.500.11750/11988
DOI
10.22677/Theses.200000286645
Degree
Master
Department
Emerging Materials Science
University
DGIST
Related Researcher
  • Author Cho, Chang-Hee Future Semiconductor Nanophotonics Laboratory
  • Research Interests Semiconductor; Nanophotonics; Light-Matter Interaction
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Collection:
Department of Emerging Materials ScienceThesesMaster


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