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 31 for “"Bi2Te3"”.
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Spin-Orbit Delays in Photoemission from Bi2Te3 and Bi2Se3
Photoemission dynamics in solid-state materials can be observed in real-time via attosecond time-resolved photoelectron spectroscopy [1]. In this work *Reconstruction of Attosecond Beating By Interference of Two-photon Transitions* (RABBITT) [2] is applied to Bi<sub>*2*</sub>Te<sub>*3*</sub> and …
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High Pressure Quantum Oscillation Study of BiTeI and Bi2Te3
The work presented in this thesis investigates the behaviour of the Rashba semi-conductor BiTeI and of the topological insulator $\text{Bi}_2\text{Te}_3\,$ under pressure. Using Shubnikov-de Haas quantum oscillation measurements, the evolution of the Fermi surface of both materials was tracked as a …
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Thermoelectric and electrical transport properties of Bi2Te3 compacted nanoparticles bulk material
… to macroscopic nanograined bulk samples. Bi2Te3 nanoparticles well known for their excellent thermoelectric and 3D TI properties serve as our model system. As key enabler for this approach, we applied a specific synthesis that creates nanoparticles with a low level of impurities and …
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Termoelektriset nanokomposiitit
… atomikerroskasvatuksella (ALD) valmistettuja Bi2Te3/Al2O3- ja Bi2Te3/polyimidi-nanorakenteita. Näytteiden koostumusta ja rakennetta analysoitiin eri menetelmillä: komposiittinäytteissä havaittiin pyyhkäisyelektronimikroskoopilla (SEM) Bi2Te3-ohutkalvoille ominaista morfologiaa ja kalvot olivat …
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Ultra low thermal conductivity in layered disordered crystalline materials
… limit to the lattice thermal conductivity of Bi2Te3 and related materials using thin films synthesized by MER. The thermal conductivities of single layer films of Bi2Te3 , Bi2Te3 and Sb-doped Bi2Te3 and multilayer films of (Bi2Te3)m(TiTe2)n and [(BixSb1-x)2Te3]m(TiTe2)n are measured by TDTR; …
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Angle-resolved photoemission studies of thin-film topological materials
… a prototypical topological insulator (TI), Bi2Te3, and a newly discovered topological Dirac semimetal (TDS), α-Sn under suitable strain. TIs and TDSs have nontrivial surface states and unique bulk electronic structures. Because of that, they possess many unusual physical properties and are …
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Semiconductor Nanomaterial Development For Photovoltaic And Thermoelectric Applications
… been conducted. For the material synthesis part, Bi2Te3-based nanocrystals have been made using both pyrolysis of organometallic method and ball milling method. Experimental parameters have been optimized to make impurity-free Bi2Te3 nanocrystals of various morphologies. Raman spectroscopy has …
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Thermodynamics of ionic liquid solvents in gas purification and exfoliation mechanisms: molecular dynamics simulation and Monte Carlo calculations
… study, the exfoliation of bismuth telluride (Bi2Te3) as a well-know thermoelectric (TE) material was investigated. In the literature, it has been experimentally and computationally proven that producing a thinner layer of Bi2Te3 increases the “figure of merit” by reducing the thermal …
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Spin polarization, circular dichroism, and robustness of topological surface states
… wird gezeigt, dass in den Materialien Bi2Se3 und Bi2Te3, in übereinstimmung mit der Literatur, die entscheidenden Charakteristika eines topologischen Ober ächenzustands vorzu nden sind: Die Ober ächenzustände dieser Sys- teme durchqueren die Bandlücke in ungerader Anzahl, sie sind nicht entartet …
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Angle-resolved photoemission and first-principles studies of topological semimetals and heterostructures
… topological heterostructures Bi2Se3/Nb and Ag/Bi/Bi2Te3. First-principles calculations are used to determine the electronic band structure of the topological semimetal Sb for various spin-orbit coupling (SOC) strengths. Transitioning to a topological state typically involves a gap reversal caused …
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The fabrication of TiO2 nanostructures on porous silicon for thermoelectric application
… Nowadays, the leading TE materials are Bi2Te3-based alloys, PbTe, PbSe, SiGe, Mg2X (X = Si, Ge, Sn), skutterudite, and half-Heusler alloys. However, there are some problems arise since most of these rare earth alloy-based TE materials, such as Bi2Te3 and PbTe, suffer from thermal and …
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Applications of Cathodoluminescence in Plasmonic Nanostructures and Ultrathin InAs Quantum Layers
… is excited due to the charge oscillation in Bi2Te3 nanotips. Plasmonic properties of Bi2Te3 nanostructures relate to the lateral size, excitation location and resonant wavelength. Finally, based on the application of hybrid plasmonic structures and resonance between edges, nanosphere …
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LOW-DIMENSIONAL CHALCOGENIDE BASED THERMOELECTRIC COMPOSITES
… alloys as templates. On the other hand, Bi2Se3, Bi2Te3, Sb2Te3 nanoplates and their derivatives were also successfully fabricated. After nanostructures were obtained, we further combine them with polymers such as polyvinylidene fluoride to guarantee their flexibility in thermoelectric devices. …
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Scanning tunneling microscopy and spectroscopy of topological materials and heterostructures in thin films and devices
… materials. A 3D topological insulator Bi2Te3 and a 2D topological insulator WTe2, grown epitaxially, are studied with atomic resolution, and their physics is probed using in-situ back gating. The development of the back-gating process in a scanning tunneling microscope is one of the …
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Theory of topological insulators and its applications
… of insulators? ^ This thesis examines HgTe and Bi2Te3 as 2D and 3D TIs respectively. Design principles for utilizing HgTe based 2D TIs as a switch and tuning the critical width is explained. Further the surface states, which are the counterpart of the edge states in a 3D TI depend on thickness …
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The synthesis and characterization of metal chalcogenide-pedot: pss polymer composites for thermal energy conversion
… for thermal energy conversion; specifically, Te, Bi2Te3, Bi2S3, and Ag2Te. The inorganic materials have high Seebeck coefficients while the PEDOT:PSS has high electrical conductivity. This approach allows for optimization of electrical conductivity of the PEDOT while still maintaining the high …
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Angle-resolved photoemission and first-principles studies of topological thin films
… in this thesis include topological Sb, Bi2Te3, Be2Se3 thin films, Bi films, and Bi/Ag surface alloy. Topological Sb films have been successfully fabricated on Si(111) substrates. By examining the connection pattern between surface states and the quantum well bulk states, our …
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Thermoelectrics : material advancements and market applications
… efficiency, which culminated in a ZT=1 with (Bi2Te3). For approximately 30 years progress stagnated. In 1993, however, new ideas emerged that called for the fabrication of low dimensional structures to enhance electron conductivity while inhibiting phonon contribution to thermal conductivity. …
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Growth, Structural and Electrical Characterization of Topological Dirac Materials
… Sb2Te3, Cr doped Sb2Te3, bilayers of Dy doped Bi2Te3/Cr doped Sb2Te3 and Cd3As2 nanowires. It was found that a seed layer of an undoped topological insulator was a crucial first step to ensure high quality growth by molecular beam epitaxy, followed by the desired stoichiometry. By physically …
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The Fabrication of Thermoelectric Materials Using Functionalised Silicon Nanoparticles
… to current thermoelectric materials (e.g. Bi2Te3) due to their abundance and low toxicity. Phenylacetylene functionalised SiNPs have been synthesised using a bottom up approach. A cold pressed pellet of this material displays an electrical conductivity of 18.1 S m-1, in addition to a high …
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