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Effect of Nitrogen on the Stability and Thermomechanical Behavior of the β Phase in Tungsten Thin Films
Effect of Nitrogen on the Stability and Thermomechanical Behavior of the β Phase in Tungsten Thin Films
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202103151
- ISBN
- 9798283140391
- DDC
- 620.11
- 저자명
- Zhao, Yue.
- 서명/저자
- Effect of Nitrogen on the Stability and Thermomechanical Behavior of the β Phase in Tungsten Thin Films
- 발행사항
- [Sl] : Cornell University, 2025
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2025
- 형태사항
- 240 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-12, Section: B.
- 주기사항
- Advisor: Baker, Shefford.
- 학위논문주기
- Thesis (Ph.D.)--Cornell University, 2025.
- 초록/해제
- 요약While tungsten is well known for having a single equilibrium crystal structure, the body-centered cubic (BCC) α phase, a metastable β phase with the A15 structure has been extensively observed in tungsten thin films. Tungsten thin films containing the β phase exhibit unique properties, such as high-temperature superconductivity and the giant spin Hall effect (GSHE), making them promising for applications in advanced electronics. However, the study and utilization of this phase has been hindered by: (1) Unclear and inconsistent deposition protocols for reliably fabricating 100% β. (2) Limited understanding in its thermal stability, including the specific conditions and atomistic mechanisms for its irreversible transformation to the stable α phase upon heating. (3) Huge stress variations with temperature that can lead to failure during device processing. (4) A general lack of knowledge on many of its fundamental material properties.To address these challenges, we have: (1) Demonstrated that high-quality β-W films with known phase and elemental compositions can be reliably and reproducibly fabricated by introducing nitrogen during sputter deposition, and established the quantitative relationship between nitrogen content and β phase volume fraction in as-deposited films. (2) Shown that increasing nitrogen content enhances the thermal stability of β-W, developed an analytical model describing the β-α phase transition in the presence of nitrogen, extracted relevant activation energies, and explained the atomistic mechanism responsible for nitrogen stabilization. (3) Systematically characterized film stress in β-W as a function of temperature and nitrogen content using high-resolution in-situ substrate curvature measurements, and linked the observed thermomechanical behavior to underlying microstructural and compositional changes. (4) Used thermoelastic stress-temperature data from substrate curvature measurements to accurately determine the coefficient of thermal expansion (CTE) and biaxial modulus of β-W as functions of nitrogen content, with errors below 3%, and further verified these results through molecular dynamics (MD) and ab-initio molecular dynamics (AIMD) simulations.
- 일반주제명
- Materials science
- 일반주제명
- Engineering
- 일반주제명
- Thermodynamics
- 키워드
- Metastable phase
- 키워드
- Thin films
- 키워드
- Tungsten
- 기타저자
- Cornell University Materials Science and Engineering
- 기본자료저록
- Dissertations Abstracts International. 86-12B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■00520260202103151
■006m o d
■007cr#unu||||||||
■020 ▼a9798283140391
■035 ▼a(MiAaPQ)AAI31996862
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a620.11
■1001 ▼aZhao, Yue.▼0(orcid)0000-0002-9319-438X
■24510▼aEffect of Nitrogen on the Stability and Thermomechanical Behavior of the β Phase in Tungsten Thin Films
■260 ▼a[Sl]▼bCornell University▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a240 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-12, Section: B.
■500 ▼aAdvisor: Baker, Shefford.
■5021 ▼aThesis (Ph.D.)--Cornell University, 2025.
■520 ▼aWhile tungsten is well known for having a single equilibrium crystal structure, the body-centered cubic (BCC) α phase, a metastable β phase with the A15 structure has been extensively observed in tungsten thin films. Tungsten thin films containing the β phase exhibit unique properties, such as high-temperature superconductivity and the giant spin Hall effect (GSHE), making them promising for applications in advanced electronics. However, the study and utilization of this phase has been hindered by: (1) Unclear and inconsistent deposition protocols for reliably fabricating 100% β. (2) Limited understanding in its thermal stability, including the specific conditions and atomistic mechanisms for its irreversible transformation to the stable α phase upon heating. (3) Huge stress variations with temperature that can lead to failure during device processing. (4) A general lack of knowledge on many of its fundamental material properties.To address these challenges, we have: (1) Demonstrated that high-quality β-W films with known phase and elemental compositions can be reliably and reproducibly fabricated by introducing nitrogen during sputter deposition, and established the quantitative relationship between nitrogen content and β phase volume fraction in as-deposited films. (2) Shown that increasing nitrogen content enhances the thermal stability of β-W, developed an analytical model describing the β-α phase transition in the presence of nitrogen, extracted relevant activation energies, and explained the atomistic mechanism responsible for nitrogen stabilization. (3) Systematically characterized film stress in β-W as a function of temperature and nitrogen content using high-resolution in-situ substrate curvature measurements, and linked the observed thermomechanical behavior to underlying microstructural and compositional changes. (4) Used thermoelastic stress-temperature data from substrate curvature measurements to accurately determine the coefficient of thermal expansion (CTE) and biaxial modulus of β-W as functions of nitrogen content, with errors below 3%, and further verified these results through molecular dynamics (MD) and ab-initio molecular dynamics (AIMD) simulations.
■590 ▼aSchool code: 0058.
■650 4▼aMaterials science
■650 4▼aEngineering
■650 4▼aThermodynamics
■653 ▼aMetastable phase
■653 ▼aPhase transformation kinetics
■653 ▼aThermal stability
■653 ▼aThermomechanical behavior
■653 ▼aThin films
■653 ▼aTungsten
■690 ▼a0794
■690 ▼a0537
■690 ▼a0348
■71020▼aCornell University▼bMaterials Science and Engineering.
■7730 ▼tDissertations Abstracts International▼g86-12B.
■790 ▼a0058
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17357225▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
