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Mapping Structural Deformations in Moire Materials Using Diffraction-Based Electron Microscopy
Mapping Structural Deformations in Moire Materials Using Diffraction-Based Electron Microscopy
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20250211151438
- ISBN
- 9798384447566
- DDC
- 540
- 서명/저자
- Mapping Structural Deformations in Moire Materials Using Diffraction-Based Electron Microscopy
- 발행사항
- [Sl] : University of California, Berkeley, 2024
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2024
- 형태사항
- 197 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-04, Section: B.
- 주기사항
- Advisor: Bediako, D. Kwabena.
- 학위논문주기
- Thesis (Ph.D.)--University of California, Berkeley, 2024.
- 초록/해제
- 요약Moire superlattices, formed by vertically stacking atomically thin van der Waals layers with a slight interlayer rotation and/or lattice constant difference, are a powerful platform for modulating the physicochemical behavior of two-dimensional solids. While the optical, electronic, and magnetic properties of moire materials can be intentionally tuned by changing the extent of crystallographic mismatch between constituent layers, structural perturbations such as lattice reconstruction, strain, and disorder also have a substantial impact on observed behavior. Therefore, directly measuring intrinsic structural deformations in moire superlattices, learning how to dynamically deform moire structures, and efforts toward correlative structure-property measurements are critical to understanding and controlling the emergent properties of these unique materials.In this dissertation, Chapter 1 first provides an introductory overview of recent developments in the field of two-dimensional materials and how the properties of these materials can be modified, including through construction of moire superlattices. This discussion is followed by a comprehensive look at the fundamentals of moire engineering, the role that structural deformations play in affecting moire properties, and the appeal of a diffraction-based imaging approach for linking the structure of moire architectures to observed properties and current theoretical models. Chapter 2 then describes the development of Bragg interferometry, a 4D-STEM-based imaging methodology for mapping moire structures, and the insights afforded by the methodology regarding the spontaneous lattice deformations driving reconstruction in twisted bilayer graphene, the effects of these deformations on flat band formation, and the impact of extrinsic heterostrain on reconstruction-induced strain fields. Chapter 3 explores the extension of Bragg interferometry to transition metal dichalcogenide (TMD) systems, providing evidence of distinct reconstruction mechanisms in twisted bilayer TMDs and heterobilayer TMDs. The compatibility of Bragg interferometry with different heterostructure geometries is also exploited to illuminate the effects of encapsulation layers on in-plane and out-of-plane reconstruction. Chapter 4 demonstrates the application of Bragg interferometry to functional devices for the first time, specifically for mapping the spatial arrangement of polar stacking domains in twisted trilayer WSe2. This information is then complemented by operando dark-field TEM imaging that uncovers a variety of electric field-driven structural responses in different twisted trilayer polytypes. Lastly, Chapter 5 provides a summary of the reported work and an outlook for future endeavours.
- 일반주제명
- Chemistry
- 일반주제명
- Condensed matter physics
- 일반주제명
- Materials science
- 키워드
- Moire structures
- 기타저자
- University of California, Berkeley Chemistry
- 기본자료저록
- Dissertations Abstracts International. 86-04B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■00520250211151438
■006m o d
■007cr#unu||||||||
■020 ▼a9798384447566
■035 ▼a(MiAaPQ)AAI31295798
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a540
■1001 ▼aVan Winkle, Madeline.
■24510▼aMapping Structural Deformations in Moire Materials Using Diffraction-Based Electron Microscopy
■260 ▼a[Sl]▼bUniversity of California, Berkeley▼c2024
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2024
■300 ▼a197 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-04, Section: B.
■500 ▼aAdvisor: Bediako, D. Kwabena.
■5021 ▼aThesis (Ph.D.)--University of California, Berkeley, 2024.
■520 ▼aMoire superlattices, formed by vertically stacking atomically thin van der Waals layers with a slight interlayer rotation and/or lattice constant difference, are a powerful platform for modulating the physicochemical behavior of two-dimensional solids. While the optical, electronic, and magnetic properties of moire materials can be intentionally tuned by changing the extent of crystallographic mismatch between constituent layers, structural perturbations such as lattice reconstruction, strain, and disorder also have a substantial impact on observed behavior. Therefore, directly measuring intrinsic structural deformations in moire superlattices, learning how to dynamically deform moire structures, and efforts toward correlative structure-property measurements are critical to understanding and controlling the emergent properties of these unique materials.In this dissertation, Chapter 1 first provides an introductory overview of recent developments in the field of two-dimensional materials and how the properties of these materials can be modified, including through construction of moire superlattices. This discussion is followed by a comprehensive look at the fundamentals of moire engineering, the role that structural deformations play in affecting moire properties, and the appeal of a diffraction-based imaging approach for linking the structure of moire architectures to observed properties and current theoretical models. Chapter 2 then describes the development of Bragg interferometry, a 4D-STEM-based imaging methodology for mapping moire structures, and the insights afforded by the methodology regarding the spontaneous lattice deformations driving reconstruction in twisted bilayer graphene, the effects of these deformations on flat band formation, and the impact of extrinsic heterostrain on reconstruction-induced strain fields. Chapter 3 explores the extension of Bragg interferometry to transition metal dichalcogenide (TMD) systems, providing evidence of distinct reconstruction mechanisms in twisted bilayer TMDs and heterobilayer TMDs. The compatibility of Bragg interferometry with different heterostructure geometries is also exploited to illuminate the effects of encapsulation layers on in-plane and out-of-plane reconstruction. Chapter 4 demonstrates the application of Bragg interferometry to functional devices for the first time, specifically for mapping the spatial arrangement of polar stacking domains in twisted trilayer WSe2. This information is then complemented by operando dark-field TEM imaging that uncovers a variety of electric field-driven structural responses in different twisted trilayer polytypes. Lastly, Chapter 5 provides a summary of the reported work and an outlook for future endeavours.
■590 ▼aSchool code: 0028.
■650 4▼aChemistry
■650 4▼aCondensed matter physics
■650 4▼aMaterials science
■653 ▼aTransition metal dichalcogenide systems
■653 ▼aPhysicochemical behavior
■653 ▼aMoire structures
■653 ▼aMapping structural deformations
■690 ▼a0485
■690 ▼a0794
■690 ▼a0611
■71020▼aUniversity of California, Berkeley▼bChemistry.
■7730 ▼tDissertations Abstracts International▼g86-04B.
■790 ▼a0028
■791 ▼aPh.D.
■792 ▼a2024
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17161738▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
