Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"carrier relaxation"”.
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Carrier relaxation in doped quantum wells
The relaxation time of an electron in a quantum well is derived within the random-phase approximation including full multi-subband and frequency dependent screening. The resulting expression encompasses both electron-electron and electron-phonon scattering taking into account the mutual …
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Charge carrier relaxation in fluorite-structured oxygen ion conductors /
… of electrical properties, attributed to charge carrier relaxation in electrical field, were observed in the obtained spectra. These data in complex plane plots resulted to depressed semicircles, which was assumed as consequence of existence of a distribution of relaxation times of charge …
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Charge Carrier Relaxation in Halide Perovskite Semiconductors for Optoelectronic Applications
… In this thesis, we study the early-time carrier relaxation and its impact on photoluminescence emission. We first study ultrafast carrier thermalization processes using 2D electronic spectroscopy and extract characteristic carrier thermalization times from below 10 fs to 85 fs. We then …
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Spin and Carrier Relaxation Dynamics in InAsP Ternary Alloys, the Spin-orbit-split Hole Bands in Ferromagnetic InMnSb and InMnAs, and Reflectrometry Measurements of Valent Doped Barium Titanate
… of devices requires extensive knowledge of carrier and spin dynamics. Thus, I have performed time and polarization resolved pump-probe spectroscopy on InAsP with various compositions. The carrier and spin relaxation time in these structures were observed and demonstrated tunability to the …
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Temporal dynamics of hot-electrons in metal films and alloys
… by transferring its energy to charge carriers with excessive kinetic energy, also known as the “hot-carriers.” The photogenerated hot-carriers are promising for applications ranging from optoelectronic devices to renewable energy. For example, recently, hot-carrier-based solar cells …
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Characterization of the Dynamics of Optically-Injected Nanostructure Lasers
… such as wavelength chirp and inherent relaxation oscillation frequency constraints impede their high-speed and long-distance capabilities. The injection-locking of semiconductor lasers improves the injected laser's operational characteristics under direct-modulation, attracting a large …
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Time-Resolved THz Magnetospectroscopy: Techniques and Applications
… some of the first time-resolved measurements of carrier relaxation via cyclotron resonance experiments in bulk Si. In these measurements we observe directly the magnetic field dependence of the carrier relaxation time, which decreases with increasing magnetic field—largely a consequence of …
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Ultraschnelle optoelektronische und Materialeigenschaften von Stickstoff-haltigem GaAs
… is investigated. The second part focuses on the relaxation dynamics of highly excited carriers. For this, the carrier relaxation dynamics in nitrogen implanted GaAs, in epitaxially grown GaAsN and in (pure) GaAs are investigated by means of pump probe measurements on a femtosecond time scale. The …
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Synthesis and Characterization of Magnetic II-VI Nanoparticles
… imaging and UV-Vis absorption spectroscopy. Spin-carrier relaxation times were determined using a superconducting quantum interference device (SQUID) magnetometer.
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Nanoscale heat conduction with applications in nanoelectronics and thermoelectrics
… to the mean free path and wavelength of energy carriers (electrons, photons, phonons, and molecules) or the time of interest is on the same order as the carrier relaxation time, conventional heat transfer theory is no longer valid. Tremendous progress has been made in the past two decades to …
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Optical studies of III-V quantum wires grown by strain induced lateral ordering (SILO) process
… recombination up to the room temperature. Carrier relaxation in quantum wires is studied for the intermediate temperature range. A characterization technique is developed to estimate the extent and shape of the spontaneously created composition modulation. The technique, based on resonant …
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Charge Carrier Dynamics of Lead Halide Perovskites Probed with Ultrafast Spectroscopy
… this thesis, we investigate the nature of charge carrier generation, relaxation and recombination in a range of lead halide perovskites. We focus on understanding whether the photophysical behaviour of these perovskite materials is like that of highly-ordered inorganic crystalline semiconductors …
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STM Study of Interfaces and Defects in 2D Materials
… would provide critical insight into tuning of carrier mobility, charge carrier relaxation, and electron-hole recombination rates by defect engineering or varying growth condition in few-layer 1T-PtSe2 and other related 2D materials.
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Coupling of the electrical, mechanical and optical response in polymer/liquid-crystal composites
… effect is studied by means of dielectric relaxation spectroscopy. Two dispersion regions are observed in the dielectric spectra of the pure P(VDF-TrFE) film. They are related to the glass transition and to a charge-carrier relaxation, respectively. In PDLC films containing 10 and 60 wt% …
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Optical and Electronic Interactions at the Nanoscale
… characterize the impact on the optically-excited carrier relaxation dynamics of cadmium selenide quantum dots due to a surface treatment previously shown to increase interparticle coupling, namely the solution exchange of native, aliphatic ligands for thiocyanate followed by subsequent sample …
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Carrier dynamics of ErAs:GaBixAs1-x using infrared pump, terahertz probe spectroscopy.
… these components leads to competing pathways for carrier relaxation. While carrier dynamics in GaBiAs and ErAs:GaAs have been studied extensively, dynamics in the composite material ErAs:GaBiAs, with both ErAs and GaBiAs components, remain largely unexplored. This dissertation investigates the …
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Carrier Dynamics in Perovskite Nanocrystals
… for high-efficiency solar cells. Ultrafast carrier-phonon interactions in semiconductors represent a major loss of the excess energy of photoexcitations above the bandgap. We demonstrate approaches to suppress the relaxation process, which may allow the full photon energy to be usefully …
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Ultrafast Response of Photoexcited Carriers in Transition Metal Oxides under High Pressure
… demonstrates the existence of localized charge carriers and the corresponding persistence of a band gap. Besides the threshold behaviour for photo-induced metallization, the carrier relaxation time scale, and the linear reflectivity and transmissivity have been studied under pressure increase. An …
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Radiation Study of the Organic Photovoltaic Cell P3HT:PCBM
… mechanisms resulting in the dominant photo-carrier loss mechanism, and a detailed investigation of the radiation effects. Transient photo-voltage (TPV) measurements were utilized to evaluate carrier relaxation times in P3HT:PCBM based photo-cells over a wide range of open circuit voltages. …
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Charge and Thermoelectric Transport in Semicrystalline Conjugated Polymers and Single-Walled Carbon Nanotube Networks
… and characterizes the entropy transported by a carrier divided by its charge. Consequently, it offers insights into the transport energetics and the density of states (DoS). It can be used to identify the prevailing transport mechanisms, such as phonon-assisted hopping between localized states …
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