Дисертації з теми "Semiconducting material"
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Ahmad, Nisar. "High-field transport in semiconducting material and devices." Thesis, Brunel University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258019.
Повний текст джерелаKozawa, Daichi. "Behavior of photocarrier in atomically thin two-dimensional semiconducting materials for optoelectronics." Kyoto University, 2015. http://hdl.handle.net/2433/199420.
Повний текст джерелаLonghin, Mattia. "Semiconducting bolometric detectors : material optimization and device design for future room temperature THz imaging arrays." Paris 6, 2009. http://www.theses.fr/2009PA066076.
Повний текст джерелаCALASCIBETTA, ADIEL MAURO. "SUSTAINABLE SYNTHETIC METHODOLOGIES FOR THE PREPARATION OF ORGANIC SEMICONDUCTING MATERIALS: ORGANIC (OPTO)ELECTRONICS GROWING “GREEN”." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/312085.
Повний текст джерелаThe worldwide demand for energy-efficient and high-performing (opto)electronics, along with the increasing need for economically feasible and environmentally friendly chemistry, both require semiconducting materials that are both scalable and sustainable. The concern with waste generation and toxic/hazardous chemicals usage has already moulded many operations in chemical and manufacturing industries. To date, common syntheses to access organic semiconductors require the use of large quantities of toxic and/or flammable organic solvents, often involving reagents and by-products that are harmful to health and environment. Research in the field of organic electronics is now increasingly focusing on the development of new sustainable methodologies that allow to prepare active materials in a more efficiently way, caring further on safety and sustainability associated with production processes. The immediate approach applicable consist on the removal, or at least on the minimization, of harmful and toxic substances commonly employed within standard processes. The big elephant in the room in the synthesis of active materials is the amount of organic solvent employed, which could ideally be reduced by using aqueous solution of surfactants: in these nano/micro heterogeneous environments organic transformations can happen and often with unprecedent efficiency. Clearly, the process occur not through the dissolution of the reagents (starting materials and catalyst) but from their dispersion in water. Kwon as “micellar catalysis”, this strategy has proven to be highly effective on improving sustainability becoming a prominent topic in modern organic synthesis. In particular, the micellar catalysis strategy is compatible with the most common modern strategies employed for C-C and C-heteroatom bonds forming reactions and allow to perform reactions with high yields, in water and under very mild conditions. Nonetheless, the use of such method in the field of organic semiconductors is still limited, with only few relevant examples reported in literature concerning the preparation of π-conjugated molecular and polymeric materials. This Thesis describes the importance of introducing sustainability in the synthesis of organic semiconductors, satisfying several principles of the green chemistry guidance. Our research purpose is not to provide an exhaustive list of examples of such chemistry, but rather to identify a few key developments in the field that seem especially suited to large-scale synthesis. Then, the discussion will consider the synthetic approaches typically employed to access semiconducting materials with extended π-conjugated structures. In particular, the discussion will involve the well-known Pd-catalysed cross-coupling techniques. Finally, the topic of the work will focus on micro-heterogeneous environments as a new tool for introducing sustainability in the preparation of active materials in water, satisfying several criteria relevant to green chemistry. On my opinion, the micellar catalysis approach constitute today the more promising method to lower the overall cost and environmental impact in the production of organic semiconductors without affecting yields, purity, and device performance.
Fix, Aaron. "Synthesis and Properties of Indenofluorene and Diindenothiophene Derivatives for Use as Semiconducting Materials in Organic Electronic Devices." Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/13444.
Повний текст джерела2015-10-10
Burwood, Ryan Paul. "Towards semiconducting hybrid framework materials." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648156.
Повний текст джерелаZhang, Yu. "Fabrication, structural and spectroscopic studies of wide bandgap semiconducting nanoparticles of ZnO for application as white light emitting diodes." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI046.
Повний текст джерелаThe present thesis studies ZnO nanoparticles embedded in a mesospheric polyacrylic acid (PAA) matrix synthesized via a hydrolysis protocol. The mesospheric ZnO/PAA hybrid structure was previously proved efficient in emitting visible light in a broad range, which results from the deep-level intrinsic defects in ZnO nanocrystals. To further tune the photoluminescence (PL) spectrum and improve the PL quantum yield (PL QY) of the material, metal-doped ZnO and silica-coated ZnO/PAA are fabricated independently. For ZnO doped with metallic elements, the nature, concentration, size and valence of the dopant are found to affect the formation of the mesospheres and consequently the PL and PL QY. Ions larger than Zn2+ with a higher valence tend to induce larger mesospheres and unembedded ZnO nanoparticles. Doping generally leads to the quenching of PL, but the PL spectrum can still be tuned in a wide range (between 2.46 eV and 2.17 eV) without degrading the PL QY by doping small ions at a low doping concentration (0.1 %). For silica-coated ZnO/PAA, an optimal coating correlatively depends on the amount of TEOS and ammonia in the coating process. The amount of TEOS does not affect the crystal structure of ZnO or the PL spectrum of the material, but high concentration of ammonia can degrade the PAA mesospheres and thicken the silica shell. A thin layer of silica that does not absorb too much excitation light but completely covers the mesospheres proves to be the most efficient, with a drastic PL QY improvement of six times. Regarding the application, the materials suffer from thermal quenching at temperatures high up to 100°C, at which white light emitting diodes (WLEDs) generally operates. However, silica-coated ZnO/PAA induces higher emission intensity at room temperature to make up for the thermal quenching
Yang, Changduk. "Conjugated semiconducting organic materials for electronic applications." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=98159641X.
Повний текст джерелаKrishnamurthy, Rajesh. "Passivation of GaAs and GaInAsP semiconducting materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/NQ31174.pdf.
Повний текст джерелаYang, Hui. "Modelling charge transport in organic semiconducting materials." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10062018/.
Повний текст джерелаSucharitakul, Sukrit. "2D ELECTRONIC SYSTEMS IN LAYERED SEMICONDUCTING MATERIALS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1491497351482802.
Повний текст джерелаRoot, Samuel E. "Mechanical Properties of Semiconducting Polymers." Thesis, University of California, San Diego, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10745535.
Повний текст джерелаMechanical softness and deformability underpin most of the advantages offered by semiconducting polymers. A detailed understanding of the mechanical properties of these materials is crucial for the design and manufacturing of robust, thin-film devices such as solar cells, displays, and sensors. The mechanical behavior of polymers is a complex function of many interrelated factors that span multiple scales, ranging from molecular structure, to microstructural morphology, and device geometry. This thesis builds a comprehensive understanding of the thermomechanical properties of polymeric semiconductors through the development and experimental-validation of computational methods for mechanical simulation. A predictive computational methodology is designed and encapsulated into open-sourced software for automating molecular dynamics simulations on modern supercomputing hardware. These simulations are used to explore the role of molecular structure/weight and processing conditions on solid-state morphology and thermomechanical behavior. Experimental characterization is employed to test these predictions—including the development of simple, new techniques for rigorously characterizing thermal transitions and fracture mechanics of thin films.
Mullins, J. T. "Properties of Tellurium-based II-VI semiconducting materials." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6004/.
Повний текст джерелаYusoff, Rashid Bin Mohd. "Magnetic field effect in organic semiconducting materials and devices." reponame:Repositório Institucional da UFPR, 2011. http://hdl.handle.net/1884/26437.
Повний текст джерелаGardecka, A. J. "Synthesis and characterisation of niobium doped TiO2 semiconducting materials." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1528770/.
Повний текст джерелаHe, Wei. "Ultrafast dynamics of photoexcited carriers in semiconducting nano materials." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6064/.
Повний текст джерелаLiu, Qian. "Rational molecular design for multi-functional organic semiconducting materials." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/208254/1/Qian_Liu_Thesis.pdf.
Повний текст джерелаDusastre, Vincent Jean-Marie. "Semiconducting oxide gas-sensitive resistors." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300516.
Повний текст джерелаAvelas, Resende Joao. "Copper-based p-type semiconducting oxides : from materials to devices." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI072/document.
Повний текст джерелаThe lack of a successful p-type semiconductor oxides delays the future implementation of transparent electronics and oxide-based photovoltaic devices. In the group semiconducting compounds, copper-based oxides present promising electrical, optical and manufacturing features that establish this family of materials suitable for p-type semiconductor applications. In this work, we focused on the growth of cation doped Cu2O and intrinsic CuCrO2 thin films, aiming for enhancements of their optical and electrical response. Furthermore, we implemented these oxide films into pn junction devices, such as solar cells and UV photodetectors.In the work on Cu2O, we achieved the incorporation of magnesium up to 17% in thin films by aerosol-assisted chemical vapor deposition, resulting in morphology changes. Electrical resistivity was reduced down to values as low as 6.6 ohm.cm, due to the increase of charge-carrier density up to 10^18 cm-3. The incorporation of magnesium had additionally an impact on the stability of the Cu2O phase. The transformation of Cu2O into CuO under oxidizing conditions is significantly postponed by the presence of Mg in the films, due to the inhibition of copper split vacancies formation. The integration into pn junctions was successfully achieved using only chemical vapor deposition routes, in combination with n-type ZnO. Nevertheless, the application of Mg-doped Cu2O in solar cells present a meager photovoltaic performance, far from the state-of-the-art reports.In the work on CuCrO2, we demonstrate the first fabrication of ZnO/CuCrO2 core-shell nanowire heterostructures using low-cost, surface scalable, easily implemented chemical deposition techniques at moderate temperatures, and their integration into self-powered UV photodetectors. A conformal CuCrO2 shell with the delafossite phase and with high uniformity is formed by aerosol-assisted chemical vapor deposition over an array of vertically aligned ZnO nanowires grown by chemical bath deposition. The ZnO/CuCrO2 core-shell nanowire heterostructures present a significant rectifying behavior, with a maximum rectification ratio of 5500 at ±1V, which is much better than similar 2D devices, as well as a high absorption above 85% in the UV region. When applied as self-powered UV photodetectors, the optimized heterojunctions exhibit a maximum responsivity of 187 µA/W under zero bias at 374 nm as well as a high selectivity with a UV-to-visible (374-550 nm) rejection ratio of 68 under an irradiance of 100 mW/cm2
Teng, Teng. "Semiconducting Materials Based on Donor/Acceptor Units for Optoelectronic Applications." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS452.pdf.
Повний текст джерелаLiquid crystalline semiconductors and narrow bandgap materials are two kinds of interesting materials for optoelectronic applications. They can be used in several type of organic electronic devices such as organic solar cells (OPV), Organic Light Emitting Diodes (OLED) and Organic Field Effect transistors (OFET). In this work, we focused on designing and synthesizing novel semiconducting materials based on donor/acceptor architectures which present either high photoluminescence and charge transport properties, or a narow bandgap for ambipolar charge transport. These materials are liquid crystalline molecules based on a benzothiadiazole acceptor core and alkoxyphenyl donor groups. The narrow bandgap molecules are based on a naphthalene diimide core and in this case flanked by benzothiadiazole units. The objective was to study their photophysical properties, charge transport properties, and to correlate this to the structural properties of the materials developed. Based on our results, we demostrated that these luminescent molecules possess liquid crystal properties with lamellar or multi-lamellar structures consisting of alternating layers of fluorescent units and high charge transport moieties. The charge transport properties measured of these compounds indicate that they have a potential for optoelectronic applications such as OFET devices. In addition, the two narrow bandgap molecules developed were found to exhibt n-type, and ambipolar charge transport properties
Mattocks, Philip. "Scanning tunnelling microscopy and atomic force microscopy of semiconducting materials." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/scanning-tunnelling-microscopy-and-atomic-force-microscopy-of-semiconducting-materials(9bc10301-2c4d-4dfb-a374-f65ee37ae23a).html.
Повний текст джерелаFerlauto, Laura. "Correlation between structural and electrical properties of organic semiconducting materials." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF009/document.
Повний текст джерелаThis thesis presents multiple characterization techniques applied to various organic materials with the ultimate goal of unraveling their structure-properties relationship once encapsulated as active materials in OFETs devices. Particular care is then dedicated to the structural characterization methods (2D-GIXRD, XRR and XRD) both from classical laboratory source and from synchrotron radiation. Various organic materials, comprising p- and n-type small molecules and polymers deposited from solution or by vacuum sublimation are investigated. In particular, the study on OFETs based two functionalized perylene isomers differing only in the shape of the alkyl side-chians demonstrates how the branched and asymmetric nature of the chains can lead to an improvement of the electrical performance with a simple post-deposition thermal treatment, while the fabrication of ambipolar polymeric devices by means of Langmir-Schaefer technique highligts the importance of the deposition method on the arrangement of the material on the substrate surface. A more unusual approach, named in-situ and real-time structural investigation, is also presented to evaluate structural modifications in organic thin films undergoing a particular process. Specifically, the structural responce of pentacene thin films to the application of VSG and VSD to the OFET and of TTF derivatives thin films to the variation of humidty were investigated
FERLAUTO, Laura. "CORRELATION BETWEEN STRUCTURAL AND ELECTRICAL PROPERTIES OF ORGANIC SEMICONDUCTING MATERIALS." Doctoral thesis, Università degli studi di Ferrara, 2015. http://hdl.handle.net/11392/2389073.
Повний текст джерелаDecataldo, Francesco <1992>. "Semiconducting Polymers for Electronic Biosensors and Biological Interfaces." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9344/1/PhD_Thesis_Complete_Decataldo.pdf.
Повний текст джерелаHsu, Ching-Ming. "High resolution SIMS analysis using a chemical bevelling technique." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243823.
Повний текст джерелаFlatten, Lucas Christoph. "Quantum electrodynamics of semiconducting nanomaterials in optical microcavities." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:a5f4797f-ea23-49e4-bd1e-2483154508d6.
Повний текст джерелаSchneck, Jude Robert. "Femtosecond electronic dephasing and population relaxation of some novel semiconducting materials." Thesis, Boston University, 2012. https://hdl.handle.net/2144/34692.
Повний текст джерелаPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
The dissipation of energy by excited carriers in semiconductors is crucial to device development. In particular, the carrier relaxation mechanisms are strongly modified by the degree of disorder introduced into the lattice via the growth process. The pump probe spectroscopic technique is ideally suited to monitor the energy dissipation process and elucidate the relaxation mechanisms contributing to the carrier decay. Additionally, phase breaking interactions of optical transitions, as measured via the photon echo spectroscopic technique, provides insight into the different homogeneous relaxation mechanisms contributing to the optical resonance. When compared to high quality semiconducting materials, the fundamental homogeneous relaxation mechanisms depend strongly on the disorder inherent in the material. The photon echo technique is ideal for quantifying the strength of these interactions. Femtosecond pump-probe responses of a GaN thin film excited above and below the UV band gap were measured to determine the kinetic relaxation pathways of carriers. A number of fluence dependent decay processes were identified, including carrier-carrier scattering, exciton decay, trapping to defect states, and hole state recovery. The characteristic timescales of these mechanisms ranged from <50 fs to >600 ps. In other measurements on GaN, two-pulse photon echoes due to the strongly dipole coupled excitons were observed as a function of temperature (1 0 - 295K). A biexponential decay of the dephasing rate was found from these measurements and attributed to free and bound excitons. The dynamics of the E22 transition of (6,5) single walled carbon nanotubes was studied over a range of fluences via pump-probe spectroscopy. A fluence dependent dephasing rate was deduced from an analysis of the pump-probe signal intensity at a fixed short delay time allowing an effective cross section for exciton-exciton interactions to be determined. The relaxation kinetics of optically excited E22 excitons was revealed by pump fluence dependent fits to the observed pump-probe responses. The model includes both Auger recombination from the E11 and E22 states due to exciton-exciton annihilation and a stretched exponential decay from E11 to the valence band. E11 and E22 diffusion coefficients and the defect density were determined from this analysis.
2031-01-01
Worch, Joshua Charles. "Well-Defined Semiconducting Materials with Stabilized Molecular Orbitals: Thiaphospholes to Polythiophenes." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/1029.
Повний текст джерелаNakamura, Tomoya. "Molecular Orientation Control of Organic Semiconducting Materials for Thin Film Electronics." Kyoto University, 2019. http://hdl.handle.net/2433/242523.
Повний текст джерелаBlanagulu, B. "Novel nanoscopic molecular materials as precursors for metal and semiconducting nanoparticles." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2016. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2066.
Повний текст джерелаCiavatti, Andrea <1986>. "Transport Properties and Novel Sensing Applications of Organic Semiconducting Crystals." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6769/1/ciavatti_andrea_tesi.pdf.
Повний текст джерелаCiavatti, Andrea <1986>. "Transport Properties and Novel Sensing Applications of Organic Semiconducting Crystals." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6769/.
Повний текст джерелаBrewster, Megan Marie. "The interplay of structure and optical properties in individual semiconducting nanostructures." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69662.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from PDF version of thesis. Vita.
Includes bibliographical references (p. 163-174).
Semiconductor nanostructures exhibit distinct properties by virtue of nano-scale dimensionality, allowing for investigations of fundamental physics and the improvement of optoelectronic devices. Nanoscale morphological variations can drastically affect overall nanostructure properties because the investigation of nanostructure assemblies convolves nanoscale fluctuations to produce an averaged result. The investigation of individual nanostructures is thus paramount to a comprehensive analysis of nanomaterials. This thesis focuses on the study of individual GaAs, AlGaAs, and ZnO nanostructures to understand the influence of morphology on properties at the nanoscale. First, the diameter-dependent exciton-phonon coupling strengths of individual GaAs and AlGaAs nanowires were investigated by resonant micro-Raman spectroscopy near their direct bandgaps. The one-dimensional nanowire architecture was found to affect exciton lifetimes through an increase in surface state population relative to volume, resulting in Fröhlich coupling strengths stronger than any previously observed. Next, ZnO nanowire growth kinetics and mechanisms were found to evolve by altering precursor concentrations. The cathodoluminescence of nanowires grown by reaction-limited kinetics were quenched at the nanowire tips, likely due to point defects associated with the high Zn supersaturation required for reaction-limited growth. Further, cathodoluminescence was quenched in the vicinity of Au nanoparticles, which were found on nanowire sidewalls due to the transition in growth mechanism, caused by excited electron transfer from the ZnO conduction band to the Au Fermi level. Finally, ZnO nanowalls were grown by significantly increasing precursor flux and diffusion lengths over that of the ZnO nanowire growth. Nanowall growth began with the Au-assisted nucleation of nanowires, whose growth kinetics was a combination of Gibbs- Thomson-limited and diffusion-limited, followed by the domination of non-assisted film growth to form nanowalls. Nanoscale morphological variations, such as thickness variations and the presence of dislocations and Au nanoparticles, were directly correlated with nanoscale variations in optical properties. These investigations prove unequivocally that nanoscale morphological variations have profound consequences on optical properties on the nanoscale. Studies of individual nano-objects are therefore prerequisite to fully understanding, and eventually employing, these promising nanostructures.
by Megan Marie Brewster.
Ph.D.
Jones, Eric James Ph D. Massachusetts Institute of Technology. "Nanoscale quantification of stress and strain in III-V semiconducting nanostructures." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98578.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 142-149).
III-V semiconducting nanostructures present a promising platform for the realization of advanced optoelectronic devices due to their superior intrinsic materials properties including direct band gap energies that span the visible light spectrum and high carrier mobilities. Additionally, the inherently high surface-to-volume ratio of nanostructures allows for the efficient relaxation of stress enabling the realization of defect free heterostructures between highly mismatched materials. As a result, nanostructures are being investigated as a route towards the direct integration of III-V materials on silicon substrates and as platforms for the fabrication of novel heterostructures not achievable in a thin film geometry. Due to their small size, however, many of the methods used to calculate stress and strain in 2D bulk systems are no longer valid as free surface effects allow for relaxation creating more complicated stress and strain fields. These inhomogeneous strain fields could have significant impacts on both device fabrication and operation. Therefore, it will be vital to develop techniques that can accurately predict and measure the stress and strain in individual nanostructures. In this thesis, we demonstrate how the combination of advanced transmission electron microscopy (TEM) and continuum modeling techniques can provide a quantitative understanding of the complex strain fields in nanostructures with high spatial resolutions. Using techniques such as convergent beam electron diffraction, nanobeam electron diffraction, and geometric phase analysis we quantify and map the strain fields in top-down fabricated InAlN/GaN high electron mobility transistor structures and GaAs/GaAsP core-shell nanowires grown by a particle-mediated vapor-liquid-solid mechanism. By comparing our experimental results to strain fields calculated by finite element analysis, we show that these techniques can provide quantitative strain information with spatial resolutions on the order of 1 nm. Our results highlight the importance of nanoscale characterization of strain in nanostructures and point to future opportunities for strain engineering to precisely tune the behavior and operation of these highly relevant structures.
by Eric James Jones.
Ph. D.
Buccheri, Alexander. "Modelling the optical properties of semiconducting nanostructures." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:67d66b15-c5b1-4bb1-806c-6cc22d0eb482.
Повний текст джерелаCarroli, Marco. "Novel materials for direct X-ray detectors based on semiconducting organic polymers." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9345/.
Повний текст джерелаKhalil, Mahmoud. "Investigation and optimization of semiconducting chromium disilicide based materials for thermoelectric applications." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS165.
Повний текст джерелаIn the context of renewable energies, which is related to the shortage of fossil energies and climate change, thermoelectricity has regained interest in recent years (1990s). The concept of this technology is the direct conversion between thermal and electrical energies. This can contribute to a progress in the industrial sector. However, the efficiency of the thermoelectric materials, denoted ZT (figure of merit), is not sufficient for large scale applications. Nevertheless, thermoelectricity can be found in the niche market sector where other criteria are taken into account such as the abundance of the raw elements, their price and toxicity. Several families meet these criteria with the silicides as inorganics materials and conductive polymers as organics materials being the most favorable. The objective of this dissertation was to investigate the chromium disilicide (CrSi2) and PEDOT:PSS.Among the silicides, CrSi2 stands as a promising candidate for thermoelectric applications. However, its relatively high thermal conductivity compared to the conventional materials is considered as a drawback. Therefore, we were interested in nanostructuration in order to reduce this thermal conductivity. Nanostructured CrSi2 is synthesized by arc melting followed by mechanical milling or mechanical alloying with a grain size of 10-15 nm. These powders have a good chemical stability up to 1073 K. Above this temperature, secondary phases, such as CrSi, are formed. SPS processing permits to efficiently densify our pellets up to 94% while maintaining nanometric grain size (30-45 nm). This leads to a reduction of the thermal conductivity by a factor of 2 compared to bulk CrSi2. However, the Figure of merit (ZT) does not improve as the electrical resistivity increases.DFT calculations predict that some doping elements have potentiality to improve CrSi2 electronic structure. Therefore, Cr1-xTixSi2, Cr1-xZrxSi2 et Cr1-xMoxSi2 alloys are synthesized in order to enhance the thermoelectric properties of CrSi2. At RT, The power factor of Cr0.9Ti0.1Si2 seems not to be improved compared to nano-CrSi2 for a porosity of 11%. On the other hand, 2% Zr doping improved the power factor by 1.7 at RT for a porosity of 30%. It also seems that for 0% porosity, the power factor of Cr0.98Zr0.02Si2 is improved by a factor 1.9 compared to bulk CrSi2. Nevertheless, an improvement could be predicted at high temperatures for Cr0.9Ti0.1Si2. Although Cr1-xZrxSi2 alloy is metastable, we were able to synthesize it by mechanical alloying up to 5%. Further optimization is needed for improving the thermoelectric performances of Ti and Zr- doped CrSi2 . On the other hand, Cr1-xMoxSi2 alloys seem to be the most promising as an increase of the Figure of merit is observed with a ZTmax reaching values larger than 0.2 for Cr0.9Mo0.1Si2 and Cr0.8Mo0.2Si2 in the temperature range of 500-700 K. These values are higher compared to the bulk but still in the same order of magnitude as for the highest ZT value report for CrSi2.We then elaborated CrSi2 based composites with Polypyrrole (PPy) and PEDOT :PSS. No significant enhancement was observed for PPy-CrSi2 composites. In order to improve the dispersion of CrSi2 in the PEDOT :PSS, we have tested the functionnalization. Preliminary tests show that grafting agents with phosphonic acid group is the most efficient by reacting with Cr. This step is very promising as no study till date reported the functionnalization approach for the elaboration of silicides based composites, especially for thermoelectric applications
Fratelli, Ilaria <1992>. "Novel Semiconducting Materials and Thin Film Technologies for High Energy Radiation Detection." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9560/1/tesi_ilariaFratelli.pdf.
Повний текст джерелаSIBILIA, MIRTA. "Organic semiconducting single crystal growth on naostructured matrices." Doctoral thesis, Università degli Studi di Trieste, 2017. http://hdl.handle.net/11368/2908140.
Повний текст джерелаGolea, Mostefa. "AB(2)C(4) semiconducting compounds crystal growth, intrinsic defects and optical properties." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5374.
Повний текст джерелаSirota, Benjamin. "Investigation into the Semiconducting and Device Properties of MoTe2 and MoS2 Ultra-Thin 2D Materials." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157626/.
Повний текст джерелаVillalpando, Páez Federico. "Raman spectroscopy of double walled carbon nanotubes with different metallic and semiconducting configurations." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59238.
Повний текст джерелаIncludes bibliographical references (p. 117-125).
A double-walled carbon nanotube (DWNT) provides the simplest system to study the interaction between concentric tubes in carbon nanotubes. The inner and outer walls of a DWNT can be metallic (M) or semiconducting (S), and each of the four possible configurations (MUM, M©S, SUS, S©M) has different electronic properties. We analyze the Raman spectra from undoped and boron-doped chemical vapor deposition-derived DWNT bundles (CVD-DWNTs) that exhibit the "coalescence inducing mode" (CIM) as they are heat treated at temperatures between 12000C and 2000'C. We then report, for the first time, detailed Raman spectroscopy experiments carried out on individual DWNTs, where both concentric tubes of the same DWNT are measured under resonance conditions. A technique is developed that combines tunable Raman spectroscopy with Raman mapping procedures and electron beam lithography to enable the acquisition of Raman spectra from the individual constituents of the same isolated DWNT. By using the technique mentioned above, we measure resonant Raman scattering from 11 individual C60-derived double wall carbon nanotubes all having inner semiconducting (6,5) tubes and various outer metallic tubes. We report that in an individual DWNT an increase in the RBM frequency of the inner tube is related to an increase in the RBM frequency of the outer tube due to a decrease in the wall to wall distance. Finally, we use 40 laser excitation energies to analyze the differences in the Raman spectra from chemical vapor deposition-derived DWNT bundles (CVD-DWNTs), fullerene-derived DWNT bundles (C₆₀-DWNTs) and individual fullerene-derived DWNTs with inner type I and type II semiconducting tubes paired with outer metallic tubes.
by Federico Villalpando Páez.
Ph.D.
Lu, Chih-Yuan. "Group III-selenides : new silicon compatible semiconducting materials for phase change memory applications /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10610.
Повний текст джерелаBhandari, Srijana. "AN ELECTRONIC STRUCTURE APPROACH TO UNDERSTAND CHARGE TRANSFERAND TRANSPORT IN ORGANIC SEMICONDUCTING MATERIALS." Kent State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=kent1606836665551399.
Повний текст джерелаMa, Yingqiao. "A Two-dimensional Semiconducting GaN-based Ferromagnetic Monolayer." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541513207541646.
Повний текст джерелаAndy, Andre Sarker. "Design, analysis, and applications of optically-activated antennas and dielectric lenses using photosensitive semiconducting materials." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/41784.
Повний текст джерелаMartinez-Morales, Alfredo Adolfo. "Synthesis, characterization and applications of novel nanomaterial systems and semiconducting nanowires." Diss., [Riverside, Calif.] : University of California, Riverside, 2010. http://proquest.umi.com/pqdweb?index=0&did=2019838541&SrchMode=2&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1273864032&clientId=48051.
Повний текст джерелаIncludes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed May 14, 2010). Includes bibliographical references. Also issued in print.
Huang, Lanqi. "Synthesis and characterization of benzodithiophene- and quinoxalinedithienothiophene-based semiconducting materials for organic solar cells." HKBU Institutional Repository, 2019. https://repository.hkbu.edu.hk/etd_oa/608.
Повний текст джерелаMiller, Derek. "Advancing electronic structure characterization of semiconducting oxide nano-heterostructures for gas sensing." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492639729205609.
Повний текст джерелаDey, Prasenjit. "Exciton Dynamics and Many Body Interactions in Layered Semiconducting Materials Revealed with Non-linear Coherent Spectroscopy." Thesis, University of South Florida, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10076073.
Повний текст джерелаAtomically thin, semiconducting transition metal dichalogenides (TMDs), a special class of layered semiconductors, that can be shaped as a perfect two dimensional material, have garnered a lot of attention owing to their fascinating electronic properties which are achievable at the extreme nanoscale. In contrast to graphene, the most celebrated two-dimensional (2D) material thus far; TMDs exhibit a direct band gap in the monolayer regime. The presence of a non-zero bandgap along with the broken inversion symmetry in the monolayer limit brands semiconducting TMDs as the perfect candidate for future optoelectronic and valleytronics-based device application. These remarkable discoveries demand exploration of different materials that possess similar properties alike TMDs. Recently, III-VI layered semiconducting materials (example: InSe, GaSe etc.) have also emerged as potential materials for optical device based applications as, similar to TMDs, they can be shaped into a perfect two-dimensional form as well as possess a sizable band gap in their nano-regime. The perfect 2D character in layered materials cause enhancement of strong Coulomb interaction. As a result, excitons, a coulomb bound quasiparticle made of electron-hole pair, dominate the optical properties near the bandgap. The basis of development for future optoelectronic-based devices requires accurate characterization of the essential properties of excitons. Two fundamental parameters that characterize the quantum dynamics of excitons are: a) the dephasing rate, γ, which represents the coherence loss due to the interaction of the excitons with their environment (for example- phonons, impurities, other excitons, etc.) and b) excited state population decay rate arising from radiative and non-radiative relaxation processes. The dephasing rate is representative of the time scale over which excitons can be coherently manipulated, therefore accurately probing the source of exciton decoherence is crucial for understanding the basic unexplored science as well as creating technological developments. The dephasing dynamics in semiconductors typically occur in the picosecond to femtosecond timescale, thus the use of ultrafast laser spectroscopy is a potential route to probe such excitonic responses.
The focus of this dissertation is two-fold: firstly, to develop the necessary instrumentation to accurately probe the aforementioned parameters and secondly, to explore the quantum dynamics and the underlying many-body interactions in different layered semiconducting materials. A custom-built multidimensional optical non-linear spectrometer was developed in order to perform two-dimensional spectroscopic (2DFT) measurements. The advantages of this technique are multifaceted compared to regular one-dimensional and non-linear incoherent techniques. 2DFT technique is based on an enhanced version of Four wave mixing experiments. This powerful tool is capable of identifying the resonant coupling, probing the coherent pathways, unambiguously extracting the homogeneous linewidth in the presence of inhomogeneity and decomposing a complex spectra into real and imaginary parts. It is not possible to uncover such crucial features by employing one dimensional non-linear technique.
Monolayers as well as bulk TMDs and group III-VI bulk layered materials are explored in this dissertation. The exciton quantum dynamics is explored with three pulse four-wave mixing whereas the phase sensitive measurements are obtained by employing two-dimensional Fourier transform spectroscopy. Temperature and excitation density dependent 2DFT experiments unfold the information associated with the many-body interactions in the layered semiconducting samples.