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From THz to DUV: Exploring Emission Properties in Biofilm and Semiconductor Structures With Spectroscopy.
From THz to DUV: Exploring Emission Properties in Biofilm and Semiconductor Structures With Spectroscopy.
상세정보
- 자료유형
- 학위논문(국외)
- 기본표목-개인명
- 표제와 책임표시사항
- From THz to DUV: Exploring Emission Properties in Biofilm and Semiconductor Structures With Spectroscopy.
- 발행, 배포, 간사 사항
- 발행, 배포, 간사 사항
- 형태사항
- 143 p.
- 일반주기
- Source: Dissertations Abstracts International, Volume: 87-03, Section: B.
- 일반주기
- Advisor: Norris, Theodore B.
- 학위논문주기
- Thesis (Ph.D.)--University of Michigan, 2025.
- 요약 등 주기
- 요약Optical spectroscopy enables non-destructive detection of the electromagnetic (EM) signal from the samples, making it suitable for sensitive biological and semiconductor systems. Excited by sources such as optical pumping, thermal energy or metabolic energy, samples emit signals across a broad spectral range. Analyzing these emissions reveals microscopic material properties and carrier behavior. In this dissertation, we applied advanced spectroscopic techniques to explore emission properties in two important emerging physical systems, Staph Aureus biofilm system and III-nitride nanostructures system.By using Terahertz Fourier Transform Infrared spectroscopy (THz-FTIR) together with a 1.6K Liquid Helium (LHe) bolometer detector, we observe a positive emission signal near 0.6 THz and a smaller negative emission signal near 0.8 THz, which is compared to the thermal radiation, from the Staph Aureus biofilm grown in PNG media. The pattern is consistent with the absorption spectrum pattern of the biofilm and the predicted vibration modes from molecular dynamics (MD) simulations of α1 PSM structure, which is a crucial component of the biofilm. The consistency suggests the potential bacterial communication mechanism using EM signal.We study III-nitride nanostructures with optical spectroscopy to understand carrier dynamics in two applications. In the red-emitting InGaN/GaN micro-LED heterostructure nanowires, both steady-state and time-resolved photoluminescence (TRPL) measurements reveal a lateral carrier transfer from the In-poor c-plane region to the In-rich semipolar plane region. This transfer process occurs within tens of picoseconds and is supported by the temperature-dependent behaviors of the PL center at 600 nm (c-plane) and 650 nm (semipolar plane). A delayed PL emission around 10 ps in the semipolar region further validates the process. Arrhenius analysis shows a low activation energy (~6 meV) of the process, which arises from the indium disorder.In p-type InGaN nanostructures designed for photocatalytic water splitting, we directly observe the rapid carrier separation process by combining the step-function like time-resolved differential reflectivity (TRDR) signal and rapid TRPL decay within tens of ps time range after the initial excitation. The weak dependence on excitation power and temperature validates the connection between TRPL signal decay and carrier separation, rather than trap-assisted or Auger process. The carrier dynamics in the separation process is influenced by both the strength of the internal electric field induced by band bending and the extent of localized state caused by indium composition fluctuation. Carriers in deeper localized states and weaker band bending experience reduced drift and exhibit longer PL decay time. This helps us understand why an optimal Mg doping is needed for efficient water splitting. The PL behaviors of nanostructures under water immersion, catalytic reaction, or effect of nanowire aging are also studied to validate the lateral ultrafast carrier separation process.
- 주제명부출표목-일반주제명
- 주제명부출표목-일반주제명
- 주제명부출표목-일반주제명
- 주제명부출표목-일반주제명
- 비통제 색인어
- 비통제 색인어
- 비통제 색인어
- 비통제 색인어
- 부출표목-단체명
- 기본자료저록
- Dissertations Abstracts International. 87-03B.
- 전자적 위치 및 접속
- 원문정보보기
MARC
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■040 ▼aMiAaPQ▼cMiAaPQ
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■1001 ▼aShen, Yifan.
■24510▼aFrom THz to DUV: Exploring Emission Properties in Biofilm and Semiconductor Structures With Spectroscopy.
■260 ▼a[S.l.]▼bUniversity of Michigan. ▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a143 p.
■500 ▼aSource: Dissertations Abstracts International, Volume: 87-03, Section: B.
■500 ▼aAdvisor: Norris, Theodore B.
■5021 ▼aThesis (Ph.D.)--University of Michigan, 2025.
■520 ▼aOptical spectroscopy enables non-destructive detection of the electromagnetic (EM) signal from the samples, making it suitable for sensitive biological and semiconductor systems. Excited by sources such as optical pumping, thermal energy or metabolic energy, samples emit signals across a broad spectral range. Analyzing these emissions reveals microscopic material properties and carrier behavior. In this dissertation, we applied advanced spectroscopic techniques to explore emission properties in two important emerging physical systems, Staph Aureus biofilm system and III-nitride nanostructures system.By using Terahertz Fourier Transform Infrared spectroscopy (THz-FTIR) together with a 1.6K Liquid Helium (LHe) bolometer detector, we observe a positive emission signal near 0.6 THz and a smaller negative emission signal near 0.8 THz, which is compared to the thermal radiation, from the Staph Aureus biofilm grown in PNG media. The pattern is consistent with the absorption spectrum pattern of the biofilm and the predicted vibration modes from molecular dynamics (MD) simulations of α1 PSM structure, which is a crucial component of the biofilm. The consistency suggests the potential bacterial communication mechanism using EM signal.We study III-nitride nanostructures with optical spectroscopy to understand carrier dynamics in two applications. In the red-emitting InGaN/GaN micro-LED heterostructure nanowires, both steady-state and time-resolved photoluminescence (TRPL) measurements reveal a lateral carrier transfer from the In-poor c-plane region to the In-rich semipolar plane region. This transfer process occurs within tens of picoseconds and is supported by the temperature-dependent behaviors of the PL center at 600 nm (c-plane) and 650 nm (semipolar plane). A delayed PL emission around 10 ps in the semipolar region further validates the process. Arrhenius analysis shows a low activation energy (~6 meV) of the process, which arises from the indium disorder.In p-type InGaN nanostructures designed for photocatalytic water splitting, we directly observe the rapid carrier separation process by combining the step-function like time-resolved differential reflectivity (TRDR) signal and rapid TRPL decay within tens of ps time range after the initial excitation. The weak dependence on excitation power and temperature validates the connection between TRPL signal decay and carrier separation, rather than trap-assisted or Auger process. The carrier dynamics in the separation process is influenced by both the strength of the internal electric field induced by band bending and the extent of localized state caused by indium composition fluctuation. Carriers in deeper localized states and weaker band bending experience reduced drift and exhibit longer PL decay time. This helps us understand why an optimal Mg doping is needed for efficient water splitting. The PL behaviors of nanostructures under water immersion, catalytic reaction, or effect of nanowire aging are also studied to validate the lateral ultrafast carrier separation process.
■590 ▼aSchool code: 0127.
■650 4▼aPhysics.
■650 4▼aEngineering.
■650 4▼aNanotechnology.
■650 4▼aBiophysics.
■653 ▼aNanostructures
■653 ▼aCarrier dynamics
■653 ▼aBiofilm emission
■653 ▼aPhotocatalytic water splitting
■690 ▼a0537
■690 ▼a0605
■690 ▼a0786
■690 ▼a0652
■71020▼aUniversity of Michigan▼bElectrical and Computer Engineering.
■7730 ▼tDissertations Abstracts International▼g87-03B.
■790 ▼a0127
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17359863▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
