Littérature scientifique sur le sujet « Narrow band gap »
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Articles de revues sur le sujet "Narrow band gap"
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Cui, Qiuhong, et Guillermo C. Bazan. « Narrow Band Gap Conjugated Polyelectrolytes ». Accounts of Chemical Research 51, no 1 (14 décembre 2017) : 202–11. http://dx.doi.org/10.1021/acs.accounts.7b00501.
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Henson, Zachary B., Gregory C. Welch, Thomas van der Poll et Guillermo C. Bazan. « Pyridalthiadiazole-Based Narrow Band Gap Chromophores ». Journal of the American Chemical Society 134, no 8 (17 février 2012) : 3766–79. http://dx.doi.org/10.1021/ja209331y.
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Filonov, A. B., D. B. Migas, V. L. Shaposhnikov, V. E. Borisenko et A. Heinrich. « Narrow-gap semiconducting silicides : the band structure ». Microelectronic Engineering 50, no 1-4 (janvier 2000) : 249–55. http://dx.doi.org/10.1016/s0167-9317(99)00289-0.
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Walukiewicz, Wladek. « Narrow band gap group III-nitride alloys ». Physica E : Low-dimensional Systems and Nanostructures 20, no 3-4 (janvier 2004) : 300–307. http://dx.doi.org/10.1016/j.physe.2003.08.023.
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Hayase, Shuzi. « Perovskite solar cells with narrow band gap ». Current Opinion in Electrochemistry 11 (octobre 2018) : 146–50. http://dx.doi.org/10.1016/j.coelec.2018.10.017.
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Galaiko, V. P., E. V. Bezuglyi, E. N. Bratus’ et V. S. Shumeiko. « Relaxation processes and kinetic phenomena in narrow-gap superconductors ». Soviet Journal of Low Temperature Physics 14, no 4 (1 avril 1988) : 242–44. https://doi.org/10.1063/10.0031925.
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The possibility of using the two-band superconductor model1 by taking into consideration the electron scattering at the lattice defects and the correlation interaction of the wide- and narrow-band electrons for describing the kinetic properties of high-Tc superconductors (HTS) in normal state is discussed. Specific features of the relaxation processes in the electron system of a narrow-band conductor, viz. the non-Born impurity scattering in the region of band overlapping, and an anomalous increase in the electron–electron scattering for a partially filled narrow band, are explained. The temperature dependence of resistance, caused by the interference of various relaxation mechanisms, contains a broad-linear region typical of HTS, while the thermoelectric coefficient has an anomalously large value which reverses its sign upon a variation of temperature and electron concentration. A comparison is made between the kinetic and thermodynamic properties of the two-band model for different values of its microscopic parameters.
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Dashevsky, Z., V. Kasiyan, S. Asmontas, J. Gradauskas, E. Shirmulis, E. Flitsiyan et L. Chernyak. « Photothermal effect in narrow band gap PbTe semiconductor ». Journal of Applied Physics 106, no 7 (octobre 2009) : 076105. http://dx.doi.org/10.1063/1.3243081.
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Jenekhe, Samson A. « A class of narrow-band-gap semiconducting polymers ». Nature 322, no 6077 (juillet 1986) : 345–47. http://dx.doi.org/10.1038/322345a0.
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Sofo, J. O., et G. D. Mahan. « Electronic structure ofCoSb3:A narrow-band-gap semiconductor ». Physical Review B 58, no 23 (15 décembre 1998) : 15620–23. http://dx.doi.org/10.1103/physrevb.58.15620.
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Mahanti, S. D., Khang Hoang et Salameh Ahmad. « Deep defect states in narrow band-gap semiconductors ». Physica B : Condensed Matter 401-402 (décembre 2007) : 291–95. http://dx.doi.org/10.1016/j.physb.2007.08.169.
Texte intégralThèses sur le sujet "Narrow band gap"
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VALLONE, MARCO ERNESTO. « Physics-based simulation of narrow and wide band gap photonic devices ». Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2639782.
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Historically, infrared (IR) detector technologies are connected mainly with controlling and night-vision problems: in a first stage, applications concerned simply with detection of IR radiation, but very soon capabilities to form IR images were developed, opening the way to systems for recognition and surveillance, especially for military purposes. Since the last decade of the twentieth century, the use of IR imaging systems for civil and peaceful purposes have increased continuously: these include medical and industrial applications, detection of earth resources, earth and universe sciences, etc. As an example, IR imaging is widely used in astronomy, to study interstellar medium and first-stages of stellar evolution; in medicine, IR thermography – IR imaging of the human body – is employed to detect cancers or other trauma; IR detectors are also widely used in automotive industry, chemical process monitoring, global monitoring of environmental pollution and climate changes, etc. The discovery in 1959 by Lawson and co-workers of the wide tunability of the HgCdTe alloy allowed this compound to become one of the most important and versatile materials for detector applications over the entire IR range. A critical contribution to research is given by Technology Computer-Aided Design (TCAD), modeling and simulation. In the first part of this thesis, I present the main part of my research activity, focused on the development of abilities and methodologies for the simulation of realistic three-dimensional HgCdTe-based infrared photodetectors. The purpose is the investigation of generation-recombination (GR) mechanisms and modeling of spectral photoresponse in narrow-gap HgCdTe-based photodetectors, with one-, two and three-dimensional (1D, 2D, 3D) realistic TCAD models (Chapters 1-5).
Another important topic of industrial research in semiconductor physics deals with nitride-based light-emitting diodes (LEDs). From automotive to streetlights, from lights in our houses to the displays of TVs and smartphones, LED-based technology is making its way in the market. This proliferation would have been impossible without GaN-based LEDs, whose invention by Isamu Akasaki, Hiroshi Amano and Shuji Nakamura has been rewarded with the 2014 Nobel Prize in Physics. Nevertheless, GaN-based LEDs performanceis limited by a reduction (droop) of their internal quantum efficiency (IQE) as the driving current density is increased beyond 10 A/cm2, whose physical origin is still under intense debate. In the second part of this thesis, I present a quantum model, based on condensed matter many-body theory, that allowed to obtain the electron capture time and hot-electron intraband relaxation times in a quantum well (QW)-barrier heterostructure, for longitudinal optic (LO) phonon emission, as function of carrier density. The interaction was described in the Single Plasmon Pole of the Random Phase Approximation, retaining the full density-, energy- and wavevector-dependent form of the dielectric function (Chapters 6-7).
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Molis, Gediminas. « Investigation of the terahertz pulse generation from the narrow band gap semiconductor surfaces ». Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100623_093655-47390.
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Generation of terahertz radiation from semiconductor surfaces has great potential for investigation of physical properties of semiconductors. This work focuses on the semiconductor research when generating terahertz pulses from a variety of semiconductor surfaces. THz radiation from semiconductor surfaces can be generated on a whole range of physical mechanisms: the surface field screening, photo-Dember effect, the optical rectification, electric field induced optical rectification, plasma oscillations, coherent phonons and plasmons. A number of important semiconductor parameters such as refractive index, mobility, carrier relaxation time and higher conductivity valley positions can be measured using THz generation from semiconductor surface technique. In this work THz radiation generation mechanisms were investigated when changing excitation conditions: ambient temperature, magnetic field, laser wavelength and intensity, pulse duration. After tests with variety different semiconductors it was found that p-InAs is the best surface emitter when excitation laser wavelength is 800 nm. Using THz excitation spectroscopy the intervalley distances were measured directly, for the first time, in two InxGa1-xAs, InAs and InSb samples.THz spinduliuotės generavimas iš puslaidininkių paviršiaus turi didelį potencialą puslaidininkių fizikinėms savybėms tirti. Šis darbas skiriamas puslaidininkių tyrimams generuojant THz impulsus iš jų paviršių, apšviestų femtosekundiniais lazerio impulsais. THz spinduliuotė iš puslaidininkių paviršių gali būti generuojama dėl visos eilės fizikinių mechanizmų: paviršinio lauko ekranavimo, foto-Demberio efekto, optinio lyginimo, elektriniu lauku indukuoto optinio lyginimo, plazminių svyravimų, koherentinių fononų ir plazmonų. Tiriant THz spinduliuotės generacijos mechanizmus galima išmatuoti daug svarbių puslaidininkių parametrų, tokių kaip lūžio rodiklis, judris, krūvininkų gyvavimo trukmė, aukštesniųjų laidumo slėnių padėtys. Darbo metu tirti THz spinduliuotės generacijos puslaidininkio paviršiuje mechanizmai keičiant žadinimo sąlygas: aplinkos temperatūrą, magnetinį lauką, žadinančio lazerio bangos ilgį ir intensyvumą, bei impulso trukmę. Ištyrus visą eilę įvairių puslaidininkių nustatyta, kad geriausias THz spinduliuotės emiteris žadinant 800 nm bangos ilgio spinduliuote yra p-InAs. Pirmą kartą THz žadinimo spektroskopijos metodu tiesiogiai išmatuoti tarpslėniniai atstumai InxGa1-xAs , InAs ir InSb bandiniuose.
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Sapkota, Gopal. « Synthesis Strategies and a Study of Properties of Narrow and Wide Band Gap Nanowires ». Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc499984/.
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Various techniques to synthesize nanowires and nanotubes as a function of growth temperature and time were investigated. These include growth of nanowires by a chemical vapor deposition (CVD) system using vapor-liquid-solid (VLS) growth mechanism and electro-chemical synthesis of nanowires and nanotubes. Narrow band gap InSb Eg = 0.17 eV at room temp) nanowires were successively synthesized. Using a phase diagram, the transition of the nanowire from metallic- semiconducting- semi-metallic phase was investigated. A thermodynamic model is developed to show that the occurrence of native defects in InSb nanowires influenced by the nanowire growth kinetics and thermodynamics of defect formation. Wide band gap ZnO (Eg = 3.34 eV) and In2O3 (3.7 eV) were also synthesized. ZnO nanowires and nanotubes were successfully doped with a transition metal Fe, making it a Dilute Magnetic Semiconductor of great technological relevance. Structural and electronic characterizations of nanowires were studied for different semiconducting, metallic and semi-metallic nanowires. Electron transport measurements were used to estimate intrinsic material parameters like carrier concentration and mobility. An efficient gas sensing device using a single In2O3 nanowire was studied and which showed sensitivity to reducing gas like NH3 and oxidizing gas like O2 gas at room temperature. The efficiency of the gas sensing device was found to be sensitive to the nature of contacts as well as the presence of surface states on the nanowire.
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Kotitschke, Ralf Thomas. « The effects of band structure on recombination processes in narrow gap materials and laser diodes ». Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843643/.
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The work described in this thesis investigates the effects of bandstructure modifications, brought about by Landau confinement, hydrostatic pressure and uniaxial stress, on recombination processes in narrow-gap materials and laser diodes. The effects of Landau confinement on the characteristics of InSb-based emission devices operating at a wavelength of ~5mum at 77K were studied. The change in performance due to the magnetic field applied along both the cavity and the growth direction and thereby simulating quasi-quantum wire and quasi-quantum dot structures clearly demonstrated the benefits, such as reduced threshold and temperature sensitivity, gained by the reduced dimensionality. On the other hand, suppression of LO-phonon emission due to the discrete nature of the density of states was observed, for the first time, in an interband laser device. Interband recombination dynamics were studied in In1-xGaxSb and PbSe over a range of excited carrier densities and temperatures down to 30K. Detailed analysis of the results found that the Auger-1 mechanism is reduced in In1-xGaxSb as a function of Ga-fraction due to the increased bandgap energy, in good agreement with theoretical predictions. In PbSe, the Auger-1 rate was observed to dominate at low excited carrier concentrations in spite of near-mirror bands, and was found to be approximately constant between 300K and 70K and was seen to be quenched in the low temperature regime. Stimulated emission was seen to be the most efficient recombination mechanism at high excited carrier densities at low temperatures. The Auger coefficient in PbSe was found to be one to two orders of magnitude lower than for materials with a Kane band structure (Hg1-xCdxTe) with comparable bandgap. An experimental technique was developed which enables measurements at high hydrostatic pressures and high magnetic fields at low temperatures. Hydrostatic pressures were applied to a 1.5mum laser diode at different temperatures revealing the effects of pressure on the band structure and hence the laser characteristics. A visible laser diode was measured under the simultaneous application of hydrostatic pressure and uniaxial stress. The change in performance was satisfactorily explained in terms of leakage of carriers into the X-minimum in the cladding region, the process that has been suspected of being one of the major loss mechanisms in visible laser diodes. This copy of the thesis has been supplied on the condition that anyone who consults it is understood to recognise that the copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without the prior written consent of the author or the University (as may be appropriate).
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Anyebe, Ezekiel. « Growth of narrow band gap semiconductor nanowires on silicon and graphitic substrates by droplet epitaxy ». Thesis, Lancaster University, 2015. http://eprints.lancs.ac.uk/74590/.
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This thesis is focused on the growth of narrow band gap semiconductor nanowires (NWs) on silicon and graphite by droplet epitaxy. First, the growth conditions of In droplets suitable for the nucleation of NWs was identified. Vertically-aligned and non-tapered InAs NWs were then realized on bare Si. It is shown that the diameter and areal density of NWs are defined by the geometry of pre-deposited In droplets. The NWs exhibit a dominant PL peak associated with the band to band (BtB) emission in addition to a distinct BtB temperature dependent red-shift, strong emission efficiency (up to 2500C) and record narrow spectral linewidth of ~20 meV (at 10K) which is relatively smaller than previously reported values. This demonstrates the high optical properties of the droplet epitaxy grown InAs NWs. Vertically-aligned and non-tapered InAs1-xSbx NWs have been demonstrated on Si without the commonly used NWs stems. In addition, the effect of Sb addition to the morphology of self-catalyzed InAsSb NWs grown directly on Si is systematically investigated for the first time. It is shown that trace Sb flux significantly promotes lateral NWs growth while at the same time suppressing axial growth. Furthermore, Sb-induced crystal phase evolution is elucidated as a function of Sb content. Although, pure InAs NWs show a mixture of Wurtzite (WZ) and Zinc-Blende (ZB) phases, a crystal phase evolution from a highly polytypic InAs to a quasi-pure WZ InAsSb NWs (2-4% Sb content) and a quasi-pure ZB InAsSb NWs crystals (~10% Sb content) is demonstrated in addition to a significant reduction in the stacking fault density in as-grown NWs with increasing Sb content. The recent discovery of flexible graphene has triggered a new wave of optoelectronic revolution. In order to fully exploit the enormous potential of functional monolithic NWs/graphene hybrid structures, the optimal growth conditions for realizing morphologically and structurally superior InAs NWs on graphitic substrates has been identified. Vertically well-aligned and thin InAs NWs were obtained in a narrow growth window of 420-450oC while a high yield of NWs was realized within a restricted domain of growth rate and V/III flux ratio. Compared to the growths on Si, the graphitic substrate is shown to enhance adatom mobility and enable growth at high growth rate which is highly promising for cost-effective devices. In addition, the NWs on graphite show a significantly reduced density of defect in comparison to the growth on conventional Si substrates owing to van der Waals epitaxy growth technique resulting from the absence of dangling bonds. Moreover, high aspect ratio NWs are essential for functional device applications however, the growth of thin InAs1-xSbx NWs is extremely challenging owing to Sb-induced lateral growth. The growth of ultra-high aspect ratio InAs1-xSbx NWs (0 ≤ x ≤ 0.12) on graphite is demonstrated for the first time at highly As-rich conditions with potential for applications in ultra-sensitive, eco-friendly, flexible and cost-effective infrared photodetectors. It is shown that the graphitic thin film promotes Sb incorporation and is more favourable for InAsSb NWs growth in comparison to Si substrates. Finally, a morphological evolution from InN NCs to three dimensional (3D) InN islands is demonstrated with increasing growth temperature attributable to lowered surface free energy of the growing crystals with disproportionate growth velocities along different growth fronts.
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Wayzani, Abdel Aziz. « [Ρt]-οligοmers as nοvel dοnοrs fοr bulk heterοjunctiοn sοlar cell applicatiοn ». Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC240.
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Ce manuscrit se consacre au développement d'oligomères à base de platine en tant que nouveaux donneurs pour des cellules solaires organiques à hétérojonction en vrac, dans le but d'améliorer leurs performances par le biais de modifications structurelles. Le travail est divisé en trois parties principales. La première partie examine comment réduire la bande interdite des [Pt]-oligomères en modifiant la structure du ligand. Cette adaptation vise à accroître la longueur de conjugaison, la planéité, la stabilisation des quinones et à renforcer l'effet "push-pull", notamment grâce à l'ajout de 3,4éthylènedioxythiophène (EDOT). Cette approche a conduit à la création de nouveaux matériaux donneurs qui ont atteint une efficacité de conversion de puissance (ECP) moyenne de 14,81% avec des accepteurs non-fullérènes dans des cellules solaires à hétérojonction en vrac binaires, et de 15.97% dans des cellules ternaires à hétérojonction en vrac. La deuxième partie se concentre sur l'amélioration de l'organisation moléculaire des [Pt]-oligomères en intégrant un groupe mésogène discotique de triphénylène dans la structure conjuguée au moyen d'un espaceur. Il a été démontré que remplacer un espaceur triazole rigide par un espaceur aliphatique linéaire plus flexible améliorait les propriétés des [Pt]-oligomères, entraînant une augmentation de l'efficacité de conversion photovoltaïque, passant de 13 % à 15 %. Enfin, la troisième partie explore des pistes d'amélioration supplémentaires en synthétisant des [Pt]-oligomères dotés de longueurs de conjugaison étendues, associés à un groupe organisateur discotique relié par un espaceur aliphatique. Les ligands qui combinent l'EDOT et le groupe triphénylène, reliés par un espaceur aliphatique, ont affiché des propriétés prometteuses, soulignant ainsi l'importance de poursuivre ces travaux de synthèse pour tester et valider pleinement ces [Pt]-oligomères améliorésThis manuscript focuses on developing [Pt]-oligomers as novel donors for bulk heterojunction organic solar cells, aiming to enhance their performance through structural modifications. The work is divided into three main parts. The first part addresses the reduction of the band gap in [Pt]-oligomers by modifying the ligand structure to improve conjugation length, planarity, quinone stabilization, and the "push-pull" effect, specifically through the inclusion of 3,4ethylenedioxythiophene (EDOT). This approach led to new donor materials that achieved an average power conversion efficiency (PCE) of 14.81% with non-fullerene acceptors in binary bulk heterojunction solar cells and 15.97% in ternary bulk heterojunction cells. The second part focuses on enhancing the molecular organization of [Pt]-oligomers by integrating a triphenylene discotic mesogenic group into the conjugated backbone via a spacer. It was found that replacing a rigid triazole spacer with a more flexible linear aliphatic spacer improved the properties of the [Pt]-oligomers, resulting in an increase in the average PCE from 13.36% to 15.93%. The third part explores further improvements by synthesizing [Pt]oligomers with extended conjugated lengths and a discotic organizing group connected through an aliphatic spacer. Ligands that incorporate both EDOT and the triphenylene group, connected by an aliphatic spacer, demonstrated promising properties, suggesting the need for further synthesis to fully test and validate these improvements on [Pt]-oligomers
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Berenguer, Verdú Antonio José. « Analysis and design of efficient passive components for the millimeter-wave and THz bands ». Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/84004.
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This thesis tackles issues of particular interest regarding analysis and design of passive components at the mm-wave and Terahertz (THz) bands. Innovative analysis techniques and modeling of complex structures, design procedures, and practical implementation of advanced passive devices are presented.
The first part of the thesis is dedicated to THz passive components. These days, THz technology suffers from the lack of suitable waveguiding structures since both, metals and dielectric, are lossy at THz frequencies. This implies that neither conventional closed metallic structures used at microwave frequencies, nor dielectric waveguides used in the optical regime, are adequate solutions. Among a variety of new proposals, the Single Wire Waveguide (SWW) stands out due to its low attenuation and dispersion. However, this surface waveguide presents difficult excitation and strong radiation on bends. A Dielectric-Coated Single Wire Waveguide (DCSWW) can be used to alleviate these problems, but advantages of the SWW are lost and new problems arise.
Until now, literature has not given proper solution to radiation on bends and, on the other hand, rigorous characterization of these waveguides lacks these days. This thesis provides, for the first time, a complete modal analysis of both waveguides, appropriated for THz frequencies. This analysis is later applied to solve the problem of radiation on bends. Several structures and design procedures to alleviate radiation losses are presented and experimentally validated.
The second part of the thesis is dedicated to mm-wave passive components. These days, when implementing passive components to operate at such small, millimetric wavelengths, to ensure proper metallic contact and alignment between parts results challenging. In addition, dielectric absorption becomes significant at mm-wave frequencies. Consequently, conventional hollow metallic waveguides and planar transmission lines present high attenuation so that new topologies are being considered. Gap Waveguides (GWs), based on a periodic structure introducing an Electromagnetic Bandgap effect, result very suitable since they do not require metallic contacts and avoid dielectric losses.
However, although GWs have great potential, several issues prevent GW technology from becoming consolidated and universally used. On the one hand, the topological complexity of GWs difficulties the design process since full-wave simulations are time-costly and there is a lack of appropriate analysis methods and suitable synthesis procedures. On the other hand, benefits of using GWs instead of conventional structures are required to be more clearly evidenced with high-performance GW components and proper comparatives with conventional structures. This thesis introduces several efficient analysis methods, models, and synthesis techniques that will allow engineers without significant background in GWs to straightforwardly implement GW devices. In addition, several high-performance narrow-band filters operating at Ka-band and V-band, as well as a rigorous comparative with rectangular waveguide topology, are presented.Esta tesis aborda problemas actuales en el análisis y diseño de componentes pasivos en las bandas de onda milimétrica y Terahercios (THz). Se presentan nuevas técnicas de análisis y modelado de estructuras complejas, procedimientos de diseño, e implementación práctica de dispositivos pasivos avanzados. La primera parte de la tesis se dedica a componentes pasivos de THz. Actualmente no se disponen de guías de onda adecuadas a THz debido a que ambos, metales y dieléctricos, introducen grandes pérdidas. En consecuencia, no es adecuado escalar las estructuras metálicas cerradas usadas en microondas, ni las guías dieléctricas usadas a frecuencias ópticas. Entre un gran número de recientes propuestas, la Single Wire Waveguide (SWW) destaca por su baja atenuación y casi nula dispersión. No obstante, como guía superficial, la SWW presenta difícil excitación y radiación en curvas. El uso de un recubrimiento dieléctrico, creando la Dielecric-Coated Single Wire Waveguide (DCSWW), alivia estos inconvenientes, pero las ventajas anteriores se pierden y nuevos problemas aparecen. Hasta la fecha, no se han encontrado soluciones adecuadas para la radiación en curvas de la SWW. Además, se echa en falta una caracterización rigurosa de ambas guías. Esta tesis presenta, por primera vez, un análisis modal completo de SWW y DCSWW, adecuado a la banda de THz. Este análisis es aplicado posteriormente para evitar el problema de la radiación en curvas. Se presentan y validan experimentalmente diversas estructuras y procedimientos de diseño. La segunda parte de la tesis abarca componentes pasivos de ondas milimétricas. Actualmente, estos componentes sufren una importante degradación de su respuesta debido a que resulta difícil asegurar contacto metálico y alineamiento adecuados para la operación a longitudes de onda tan pequeñas. Además, la absorción dieléctrica incrementa notablemente a estas frecuencias. En consecuencia, tanto guías metálicas huecas como líneas de transmisión planares convencionales presentan gran atenuación, siendo necesario considerar topologías alternativas. Las Gap Waveguides (GWs), basadas en una estructura periódica que introduce un efecto de Electromagnetic Bandgap, resultan muy adecuadas puesto que no requieren contacto entre partes metálicas y evitan las pérdidas en dieléctricos. No obstante, a pesar del potencial de las GWs, varias barreras impiden la consolidación y uso universal de esta tecnología. Por una parte, la compleja topología de las GWs dificulta el proceso de diseño dado que las simulaciones de onda completa consumen mucho tiempo y no existen actualmente métodos de análisis y diseño apropiados. Por otra parte, es necesario evidenciar el beneficio de usar GWs mediante dispositivos GW de altas prestaciones y comparativas adecuadas con estructuras convencionales. Esta tesis presenta diversos métodos de análisis eficientes, modelos, y técnicas de diseño que permitirán la síntesis de dispositivos GW sin necesidad de un conocimiento profundo de esta tecnología. Asimismo, se presentan varios filtros de banda estrecha operando en las bandas Ka y V con altas prestaciones, así como una comparativa rigurosa con la guía rectangular.
Aquesta tesi aborda problemes actuals en relació a l'anàlisi i disseny de components passius en les bandes d'ona mil·limètrica i Terahercis. Es presenten noves tècniques d'anàlisi i modelatge d'estructures complexes, procediments de disseny, i implementació pràctica de dispositius passius avançats. La primera part de la tesi es focalitza en components passius de THz. Actualment no es disposen de guies d'ona adequades a THz causa que tots dos, metalls i dielèctrics, introdueixen grans pèrdues. En conseqüència, no és adequat escalar les estructures metál·liques tancades usades en microones, ni les guies dielèctriques usades a freqüències òptiques. Entre un gran nombre de propostes recents, la Single Wire Waveguide (SWW) destaca per la seua baixa atenuació i quasi nul·la dispersió. No obstant això, com a guia superficial, la SWW presenta difícil excitació i radiació en corbes. L'ús d'un recobriment dielèctric, creant la Dielecric-Coated Single Wire Waveguide (DCSWW), alleuja aquests inconvenients, però els avantatges anteriors es perden i nous problemes apareixen. Fins a la data, no s'han trobat solucions adequades per a la radiació en corbes de la SWW. A més, es troba a faltar una caracterització rigorosa d'ambdues guies. Aquesta tesi presenta, per primera vegada, un anàlisi modal complet de SWW i DCSWW, adequat a la banda de THz. Aquest anàlisi és aplicat posteriorment per evitar el problema de la radiació en corbes. Es presenten i validen experimentalment diverses estructures i procediments de disseny. La segona part de la tesi es centra en components passius d'ones mil·limètriques. Actualment, aquests components pateixen una important degradació de la seua resposta a causa de que resulta difícil assegurar contacte metàl·lic i alineament adequats per a l'operació a longituds d'ona tan menudes. A més, l'absorció dielèctrica incrementa notablement a aquestes freqüències. En conseqüència, tant guies metàl·liques buides com línies de transmissió planars convencionals presenten gran atenuació, sent necessari considerar topologies alternatives. Les Gap Waveguides (GWs), basades en una estructura periòdica que introdueix un efecte de Electromagnetic Bandgap, resulten molt adequades ja que no requereixen contacte entre parts metàl·liques i eviten les pèrdues en dielèctrics. No obstant, tot i el potencial de les GWs, diverses barreres impedixen la consolidació i ús universal d'aquesta tecnologia. D'una banda, la complexa topologia de les GWs dificulta el procés de disseny atés que les simulacions d'ona completa consumeixen molt de temps i no existeixen actualment mètodes d'anàlisi i disseny apropiats. D'altra banda, és necessari evidenciar el benefici d'utilitzar GWs mitjançant dispositius GW d'altes prestacions i comparatives adequades amb estructures convencionals. Aquesta tesi presenta diversos mètodes d'anàlisi eficients, models, i tècniques de disseny que permetran la síntesi de dispositius GW sense necessitat d'un coneixement profund d'aquesta tecnologia. Així mateix, es presenten diversos filtres de banda estreta operant en les bandes Ka i V amb altes prestacions, així com una comparativa rigorosa amb la guia rectangular.
Berenguer Verdú, AJ. (2017). Analysis and design of efficient passive components for the millimeter-wave and THz bands [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84004
TESIS
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Bovkun, Leonid. « Etude de la structure de bande de puits quantiques à base de semi-conducteurs de faible bande interdite HgTe et InAs ». Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY060/document.
Texte intégralRésumé :
Le tellurure de mercure et de cadmium (HgCdTe ou MCT) est un matériau reconnu pour la physique de la matière condensée, dont l'histoire, datant aujourd'hui de plus de cinquante ans, constitue un excellent exemple des progrès remarquables réalisés dans la recherche sur les semi-conducteurs et les semi-métaux. Notre travail est principalement motivé par l’intérêt fondamental que suscitent ces systèmes, mais notre recherche peut également avoir un impact pratique (indirect) sur la médecine, la surveillance ou la détection de l’environnement ainsi que sur les systèmes de sécurité. Cela peut aider à améliorer les performances des photodétecteurs dans la limite des grandes longueurs d'onde ou à faciliter la fabrication de dispositifs émettant de la lumière.La présente thèse de doctorat vise principalement à combler certaines des lacunes de notre compréhension de la structure de bande électronique des hétérostructures 2D et quasi-2D basées sur les matériaux HgTe/HgCdTe et InAs/InSb, qui peuvent être transformés en phase topologiquement isolante à l'aide des paramètres de croissance. Pour explorer leurs propriétés, la technique expérimentale de base, la magnéto-spectroscopie infrarouge et THz fonctionnant dans un large éventail de champs magnétiques, est combinée à des mesures complémentaires de magnéto-transport. Cette combinaison de méthodes expérimentales nous permet d’obtenir de précieuses informations sur les états électroniques non seulement à l’énergie de Fermi, mais également dans son voisinage relativement large. Diverses hétérostructures ont été étudiées avec des caractéristiques globales et/ou spécifiques déterminées principalement par les paramètres de croissance.La réponse magnéto-optique observée, due aux excitations intra-bande (résonance cyclotron) et interbandes (entre les niveaux de Landau) peut être interprétée dans le contexte d'études antérieures sur des échantillons 3D, des puits quantiques et des super-réseaux, mais également en rapport aux attentes théoriques. Ici, nous visons à obtenir une explication quantitative des données expérimentales recueillies, mais également à développer un modèle théorique fiable. Ce dernier comprend le réglage précis des paramètres de structure de bande présents dans le modèle établi de Kane, mais surtout, l'identification de termes supplémentaires pertinents (d'ordre élevé) nécessaires pour parvenir à un accord quantitatif avec nos expériences. On peut s’attendre à ce que les corrections dues à ces termes supplémentaires affectent davantage les sous-bandes de valence, généralement caractérisées par des masses effectives relativement importantes et, par conséquent, par une grande densité d’états ou, lorsque le champ magnétique est appliqué, par un espacement assez étroit (et mélange important) des niveaux de LandauMercury cadmium telluride (HgCdTe or MCT) is a time-honored material for condensed matter physics, whose history nowadays more than fifty years long may serve as an excellent example of remarkable progress made in research on semiconductors and semimetals. The ternary compound HgCdTe implies two important aspects, which largely contributed to its undoubted success in solid-states physics.The present PhD thesis primarily aims at filling some of existing gaps in our understanding of the electronic band structure in 2D and quasi-2D heterostructures based on HgTe/HgCdTe and InAs/InSb materials, which both may be tuned into topologically insulating phase using particular structural parameter. To explore their properties, the primal experimental technique, infrared and THz magneto-spectroscopy operating in a broad of magnetic fields, is combined with complementary magneto-transport measurements. This combination of experimental methods allows us to get valuable insights into electronic states not only at the Fermi energy, but also in relatively broad vicinity.The observed magneto-optical response - due to intraband (cyclotron resonance) and interband inter-Landau level excitations - may be interpreted in the context of previous studies performed on bulk samples , quantum wells and superlattices, but also compared with theoretical expectations. Here we aim at achieving the quantitative explanation of the collected experimental data, but also further developing a reliable theoretical model. The latter includes the fine-tuning of the band structure parameters present in the established Kane model, but even more importantly, identifying additional relevant (high-order) terms and finding their particular strengths, needed to achieve quantitative agreement with our experiments. One may expect that corrections due to these additional terms will more affect the valence subbands, which are in general characterized by relatively large effective masses. Consequently, valence subbands have larger density of states compared to conduction band or, when the magnetic field is applied, rather narrow spacing (and possibly large mixing) of Landau levels
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Wang, Chao-Chun, et 王朝俊. « Narrow band gap Si-based material (Si1-xGex) processes, analyses and solarcell applications ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/29003002404262592025.
Texte intégralRésumé :
碩士明道大學
材料科學與工程學系碩士班
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Abstract In this research, the hydrogenated amorphous silicon films (a-Si:H) and hydrogenated silicon germanium (a-SiGe:H) films were deposited using by High-frequency plasma enhanced chemical vapor deposition (HF-PECVD). For intrinsic Si layer research, pressure effect on the properties of Si films were investigated. The properties of intrinsic Si films such as deposition rate, crystalline fraction, absorption coefficient, band gap, dark conductivity, photo conductivity, hydrogen content and microstructure factor as function as deposition pressure. We investigated the pressure effects of growth mechanisms and properties on silicon films. High-quality both intrinsic and doped a-Si layers have been deposited in this paper. We report a narrow bandgap a-SiGe:H films with high photosensitivity using the mixture of SiH4 and GeH4 with H2 dilution. The effects of GeH4 / (SiH4 + GeH4 + H2) ratio on the properties of a-SiGe:H films are characterized by Raman spectrometer, X-ray photoelectron spectrometer, X-ray diffractometer spectrometer, Fourier transform infrared absorption spectroscopy, UV–Visible spectroscopy and scanning electron microscopy. We found that band gap decreases with increasing Ge content. We report the influence of Ge content on the properties of a-SiGe:H films and performance of p-i-n solar cells. The a-SiGe thin film solar cells with a Voc of 0.74 V, a Jsc of 9.9 mA/cm2 ,a fill factor of 0.60 and a maximum efficiency of 4.42 % were obtained.
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Reifsnider, Jason Miles 1967. « Characterization of as-grown and annealed narrow band gap nitrides grown by molecular beam epitaxy ». 2003. http://hdl.handle.net/2152/12359.
Texte intégralLivres sur le sujet "Narrow band gap"
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United States. National Aeronautics and Space Administration., dir. Further improvements in program to calculate electronic properties of narrow band gap materials : Final report. [Washington, DC : National Aeronautics and Space Administration, 1992.
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Patterson, James D. Improvement of program to calculate electronic properties of narrow band gap materials. Melbourne, FL : Florida Institute of Technology, 1991.
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T͡Sidilʹkovskiĭ, I. M. Electron spectrum of gapless semiconductors. Berlin : Springer, 1997.
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J, Kono, et Leotin J, dir. Narrow gap semiconductors : Proceedings of the 12th International Conference on Narrow Gap Semiconductors, Toulouse, France, 3-7 July 2005. New York : Taylor & Francis, 2006.
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National Aeronautics and Space Administration (NASA) Staff. Improvement of Program to Calculate Electronic Properties of Narrow Band Gap Materials. Independently Published, 2018.
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Ėlektronnyĭ spektr besshchelevykh poluprovodnikov. Sverdlovsk : Akademii͡a nauk SSSR, Uralʹskoe otd-nie, 1991.
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(Assistant), R. Dornhaus, G. Nimtz (Assistant) et B. Schlicht (Assistant), dir. Narrow-Gap Semiconductors (Springer Tracts in Modern Physics). Springer, 1985.
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Basu, Prasanta Kumar, Bratati Mukhopadhyay et Rikmantra Basu. Semiconductor Nanophotonics. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198784692.001.0001.
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Abstract Nanometre sized structures made of semiconductors, insulators and metals and grown by modern growth technologies or by chemical synthesis exhibit novel electronic and optical phenomena due to confinement of electrons and photons. Strong interactions between electrons and photons in narrow regions lead to inhibited spontaneous emission, thresholdless laser operation, and Bose Einstein condensation of exciton-polaritons in microcavities. Generation of sub-wavelength radiation by surface Plasmon-polaritons at metal-semiconductor interfaces, creation of photonic band gap in dielectrics, and realization of nanometer sized semiconductor or insulator structures with negative permittivity and permeability, known as metamaterials, are further examples in the area of nanophotonics. The studies help develop Spasers and plasmonic nanolasers of subwavelength dimensions, paving the way to use plasmonics in future data centres and high speed computers working at THz bandwidth with less than a few fJ/bit dissipation. The present book intends to serveas a textbook for graduate students and researchers intending to have introductory ideas of semiconductor nanophotonics. It gives an introduction to electron-photon interactions in quantum wells, wires and dots and then discusses the processes in microcavities, photonic band gaps and metamaterials and related applications. The phenomena and device applications under strong light-matter interactions are discussed by mostly using classical and semi-classical theories. Numerous examples and problems accompany each chapter.
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Keoghane, Stephen, et Mark Sullivan. The principles of endourology. Sous la direction de John Reynard. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199659579.003.0032.
Texte intégralRésumé :
The chapter discusses the principles of endourology outlining the principles behind the sub-specialty. Topics disused include endoscopes, cystoscopes, rigid and semi-rigid ureteroscopes, flexible ureterorenoscopes, rigid and flexible nephroscopes, disposable equipment, integrated operating theatres, narrow band imaging (NBI), theatre ergonomics, and antibiotics. Urologic endoscopes are generally of two optical designs: the rigid, rod lens system described by Hopkins, while fibre-optic imaging bundles are used in both rigid and flexible endoscopes. The rod lens system consists of a series of glass rods with polished ends with the key feature of air gaps that act as a lens. Light is carried efficiently along the rod, resulting in a clear and bright image.
Chapitres de livres sur le sujet "Narrow band gap"
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« 1. Optoelectronic properties of narrow band gap semiconductors ». Dans Advances in Condensed Matter Optics, 1–50. De Gruyter, 2015. http://dx.doi.org/10.1515/9783110307023.1.
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Singleton, John. « Bandstructure engineering ». Dans Band Theory and Electronic Properties of Solids, 65–84. Oxford University PressOxford, 2001. http://dx.doi.org/10.1093/oso/9780198506454.003.0007.
Texte intégralRésumé :
Abstract The idea of making artificial solids with bandstructures tailored to particular applications has long fascinated condensed matter physicists. In this chapter, we shall explore some of the ways in which bands with desired properties can be engineered using what has been termed ‘chemical architecture’. A very simple example of this is the use of semiconductor alloys, in which a wide-gap semiconductor and a narrow-gap semiconductor are combined to give a substance with a desired intermediate band-gap. A second example is the semiconductor superlattice or heterostructure; here, very thin layers of different semiconductors are superimposed. A third approach is to use small organic or inorganic molecular units to build up solids with desirable metallic, semiconducting or even superconducting properties. We shall treat each of these cases in turn, starting with the semiconductor systems.
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Kossut, J. « Chapter 5 Band Structure and Quantum Transport Phenomena in Narrow-Gap Diluted Magnetic Semiconductors ». Dans Semiconductors and Semimetals, 183–227. Elsevier, 1988. http://dx.doi.org/10.1016/s0080-8784(08)62421-7.
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Costas, Andreea, Nicoleta Preda, Camelia Florica et Ionut Enculescu. « Metal Oxide Nanowires as Building Blocks for Optoelectronic Devices ». Dans Nanowires - Recent Progress [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94011.
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Metal oxide nanowires have become the new building blocks for the next generation optoelectronic devices due to their specific features such as quantum confinement and high aspect ratio. Thus, they can be integrated as active components in diodes, field effect transistors, photodetectors, sensors, solar cells and so on. ZnO, a n-type semiconductor with a direct wide band gap (3.3 eV) and CuO, a p-type semiconductor with a narrow band gap (1.2–1.5 eV), are two metal oxides which were recently in the spotlight of the researchers for applications in the optoelectronic devices area. Therefore, in this chapter we focused on ZnO and CuO nanowires, the metal oxides nanowire arrays being prepared by straightforward wet and dry methods. Further, in order to emphasize their intrinsic transport properties, lithographic and thin films deposition techniques were used to integrate single ZnO and CuO nanowires into diodes and field effect transistors.
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Kumar, Umesh, Aparna Shekhar, Vaishali Arora et Parul Singh. « Synthesis and Photocatalytic Applications of Silver Sulfide Nanostructures : Recent Advancement ». Dans Smart Nanosystems - Advances in Research and Practice [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.112783.
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Silver sulfide nanoparticles belong to the family of important metal chalcogenides. Silver sulfide has been extensively studied in recent years due to its applications in various fields ranging from biosensors, infrared detectors, and optoelectronics to catalysis. Silver sulfide is considered as a potential photocatalyst due to narrow band gap energy, mechanical and thermal stability, cyclability, and ease of synthesis. Different methods have been investigated to produce various forms of silver sulfide nanoparticles. The present chapter focuses on the recent progress in synthesis of silver sulfide nanoparticles using hydrothermal method, chemical bath deposition, microwave-based approach, sonochemical method, single molecular precursor’s decomposition, and green synthesis. Moreover, the application of silver sulfide nanoparticles in photocatalytic degradation of organic dyes is discussed in details.
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P. Bhalekar, Vikram. « Quantum Dots Sensitized Solar Cell ». Dans Quantum Dots - Recent Advances, New Perspectives and Contemporary Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107266.
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In the modern and automated twenty-first century, with technological advancements, the scientific society has gifted a new alternative clean energy source (dye/quantum dot sensitized solar cells) to mankind as one of the applications of nanomaterials. Nowadays, the world is using a tremendous amount of fossil fuel for energy creation, the solar energy by using nanomaterials in the form of solar cells is a perfect alternative. In the present chapter, the emphasis has been given on the different techniques used by the researcher for synthesis of nanoparticles. The synthesis of quantum dots by simple cost-effective technique is covered with respect to PbS quantum dots. The working of quantum dot sensitized solar cells is also explained with its basic components. The narrow-band-gap semiconducting materials, which are suitable for solar cell application, are also listed in this context.
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Ginting, Dianta, et Jong-Soo Rhyee. « Optimizing Thermal Conductivity in PbTe : Nanocomposite and Alloy Approaches for Low Thermal Conductivity ». Dans Current Research in Thermal Conductivity [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.1006083.
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PbTe, a prominent thermoelectric material within the intermediate temperature range (500 K to 950 K), has displayed noteworthy potential due to its cubic rock salt crystal structure and narrow band gap of 0.32 eV. This investigation explores the quaternary system (PbTe)0.95-x-(PbSe)x-(PbS)0.05 with x = 0, 0.05, 0.10, 0.15, 0.20, 0.35, and 0.95, along with a consistent Na dopant concentration of 1 at%. The findings indicate that the inclusion of PbSe and PbS significantly reduces the lattice thermal conductivity, with the lowest value observed in (PbTe)0.75-(PbSe)0.20-(PbS)0.05, achieving 0.42 Wm−1 K−1, nearing the glass limit for bulk PbTe. A detailed examination using transmission electron microscopy (TEM) identifies nanostructuring as a critical mechanism for the observed reduction in thermal conductivity. The study’s outcomes highlight the crucial role of nanostructured precipitates in enhancing phonon scattering, thereby reducing thermal conductivity.
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Dutta, Amit Kumar. « Green Hydrogen, an Alternative Renewable Energy Source : Based on Solar-Energy-Driven Water-Splitting Technology ». Dans Lincoln Publication, 134–48. Lincoln Publication, 2024. http://dx.doi.org/10.31674/book.2024ecc.12.
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The need for zero-emission, eco-friendly hydrogen fuel has increased enormously over the years due to adverse impacts on the environment caused by conventional fuels such as natural gas, coal, oil, fossil fuels, bio-mass etc. This chapter reports the safest and most efficient route for hydrogen-fuel production based on solar-energy-driven watersplitting technology over a heterogeneous photo-catalyst. Several challenges have been made for the extension of photo-catalyst, based on nano-sized semiconducting materials such as binary and ternary metal chalcogenides nano-materials, CuS, CdS, Fe3O4, CuInO2, CuInS2, CuGaS2 and their composites with hetero-nanostructure. When the nano-structures have the ability to absorb solar-light-energy (having a narrow band gap energy < 3.6 eV), i.e., to utilise the most of the solar-spectrum, the photo-catalytic performances have increased much more. The catalytic performances of the semiconductors have also been improved for enhanced hydrogen production using nano-engineering technology, i.e., different modifications to the nano-catalyst surface and electronic energy structure, so that they can act as an efficient photo-catalyst for solar-energy driven water electrolysis to produce enhanced large-scale hydrogen-fuel. The possible mechanism of the photo-chemical processes has also been explored through the formation of free electron-hole pair (e- /h+) on suitable heterogeneous catalyst’s surface and controlling the kinetics of hydrogen evolution reaction and oxygen evolution reaction. How the proposed nano-catalyst materials have been designed to optimize solar-to-hydrogen conversion efficiency, improve the rate of hydrogen production and commercialized for the sake of society has been deliberated.
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Muhammad Khan, Waqas, et Wiqar Hussain Shah. « Thermoelectricity Properties of Tl10-x ATe6 (A = Pb) in Chalcogenide System ». Dans Thermoelectricity - Recent Advances, New Perspectives and Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.94487.
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The different elements are doping in the tellurium telluride to determine the different properties like electrical and thermal properties of nanoparticles. The chalcogenide nanoparticles can be characteristics by the doping of the different metals which are like the holes. We present the effects of Pb doping on the electrical and thermoelectric properties of Tellurium Telluride Tl10-xPbxTe6 (x = 1.000, 1.250, 1.500, 1.750, 2.000) respectively, which were prepared by solid state reactions in an evacuated sealed silica tubes. Structurally, all these compounds were found to be phase pure as confirmed by the x-rays diffractometery (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis. The thermo-power or Seebeck co-efficient (S) was measured for all these compounds which show that S increases with increasing temperature from 295 to 550 K. The Seebeck coefficient is positive for the whole temperature range, showing p-type semiconductor characteristics. Similarly, the electrical conductivity (σ) and the power factors have also complex behavior with Pb and Sn concentrations. The power factor (PF=S2σ) observed for Tl10-xPbxTe6 compounds are increases with increase in the whole temperature range (290 K-550 K) studied here. Telluride’s are narrow band-gap semiconductors, with all elements in common oxidation states, according to (Tl+) 9 (Pb3+)(Te2−)6. Phases range were investigated and determined with different concentration of Pb and Sn with consequents effects on electrical and thermal properties.
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Goody, R. M., et Y. L. Yung. « Band Models ». Dans Atmospheric Radiation. Oxford University Press, 1989. http://dx.doi.org/10.1093/oso/9780195051346.003.0006.
Texte intégralRésumé :
Radiative heating calculations in the atmosphere involve four distinguishable scales of frequency. First, there is the comparatively slow variation with frequency of the Planck function and its derivative with respect to temperature. About one-half of the radiation from a black body at terrestrial temperatures lies in a wave number range of 500 cm-1. The second scale is that of the unresolved contour of a band. For atmospheric molecules other than water vapor, the Planck function is effectively constant over a single band; water vapor bands must be divided into sections of the order of 50 cm-1 wide before this is so. For a rotating molecule, the next relevant scale of frequency is that of the spacing between rotation lines, approximately 1-5 cm-1. Finally, there is the monochromatic scale on which the absorption coefficient may be treated as a constant, and for which Lambert’s absorption law is obeyed: of the order of one-fifth of a line width ≃ 2 x 10-2 cm-1 for a gas at atmospheric pressure, down to 2 x 10-4cm-1 for a Doppler line in the middle atmosphere. This step takes us to a division of the frequency scale that, when taken together with other features of the calculation, presents a formidable computation task. Calculations can, of course, be made and are made at this limiting spectral resolution (line-by-line calculations) but, despite the fact that they are technically feasible with modern computers, such calculations are rare and are usually performed to provide a few reference cases. The great majority of investigations make use of averages over many lines, embracing spectral ranges that are small compared to a band contour (narrow-band models), or over complete bands (wide-band models), or over the entire thermal spectrum (emissivity models.) There are a number of reasons for working with spectral averages. Practical considerations are that important classes of laboratory measurements, and most atmospheric observations (e.g., satellite radiometry) are made with some spectral averaging, often comparable to that of narrow-band models.
Actes de conférences sur le sujet "Narrow band gap"
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Zhang, Yuanrong, Prince Gupta, Deming Liu, Shuang Zheng, Max Yan et Minming Zhang. « Power-efficient Metasurface Thermal Emitter for Mid-IR Gas Sensing Application ». Dans CLEO : Applications and Technology, JTh2A.50. Washington, D.C. : Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_at.2024.jth2a.50.
Texte intégralRésumé :
We propose a narrow band, power-efficient, cost-effective and on-chip mid-infrared source (at≈6.0 m) for gas sensing applications. Combined an optimized microelectromechanical system heater with a metal-insulator-metal metasurface emitter, the source works successfully.
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Malkova, Natalia, Garnett W. Bryant, Giti A. Khodaparast, Michael B. Santos et Christopher J. Stanton. « Negative-Band-Gap Quantum Dots ». Dans 15TH INTERNATIONAL CONFERENCE ON NARROW GAP SYSTEMS (NGS15). AIP, 2011. http://dx.doi.org/10.1063/1.3671699.
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Hayase, Shuzi. « Perovskite solar cells with wide band gap and narrow band gap ». Dans 4th Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics. València : Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.iperop.2020.009.
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Lhuillier, Emmanuel, Bertille Martinez, Clement livache et nicolas goubet. « Dynamics in Narrow Band Gap Nanocrystals ». Dans nanoGe Fall Meeting 2018. València : Fundació Scito, 2018. http://dx.doi.org/10.29363/nanoge.fallmeeting.2018.138.
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Lhuillier, Emmanuel, Bertille Martinez, Clement livache et nicolas goubet. « Dynamics in Narrow Band Gap Nanocrystals ». Dans nanoGe Fall Meeting 2018. València : Fundació Scito, 2018. http://dx.doi.org/10.29363/nanoge.nfm.2018.138.
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Wilke, Ingrid. « Terahertz emission from narrow band gap semiconductors ». Dans Optics East 2007, sous la direction de Mehdi Anwar, Anthony J. DeMaria et Michael S. Shur. SPIE, 2007. http://dx.doi.org/10.1117/12.735101.
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lhuillier, Emmanuel, Adrien Robin, Clement Livache, Bertille Martinez et Nicolas goubet. « Intraband transition in narrow band gap nanocrystals ». Dans nanoGe Fall Meeting 2018. València : Fundació Scito, 2018. http://dx.doi.org/10.29363/nanoge.fallmeeting.2018.164.
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lhuillier, Emmanuel, Adrien Robin, Clement Livache, Bertille Martinez et Nicolas goubet. « Intraband transition in narrow band gap nanocrystals ». Dans nanoGe Fall Meeting 2018. València : Fundació Scito, 2018. http://dx.doi.org/10.29363/nanoge.nfm.2018.164.
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Tkacheva, E. S., A. V. Dmitriev, Giti A. Khodaparast, Michael B. Santos et Christopher J. Stanton. « Calculation of PbTe Transport Coefficients in Three-Band Structures ». Dans 15TH INTERNATIONAL CONFERENCE ON NARROW GAP SYSTEMS (NGS15). AIP, 2011. http://dx.doi.org/10.1063/1.3671714.
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Khoshakhlagh, A., L. Hoglund D. Z. Ting, A. Soibel et S. D. Gunapala. « Optical Characteristics of Narrow Band Gap InAs/InAsSb Superlattices ». Dans 2018 IEEE Photonics Society Summer Topical Meeting Series (SUM). IEEE, 2018. http://dx.doi.org/10.1109/phosst.2018.8456719.
Texte intégralRapports d'organisations sur le sujet "Narrow band gap"
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Bedair, Salah M., John R. Hauser, Nadia Elmasry, Peter C. Colter, G. Bradshaw, C. Z. Carlin, J. Samberg et Kenneth Edmonson. Tunable Narrow Band Gap Absorbers For Ultra High Efficiency Solar Cells. Office of Scientific and Technical Information (OSTI), juillet 2012. http://dx.doi.org/10.2172/1146980.
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Beck, Steven, Mara Claire Tayag, Kijin Kim, Ma Concepcion Latoja, Ankita Pandey et Alexander Malaket. 2023 Trade Finance Gaps, Growth, and Jobs Survey. Asian Development Bank, septembre 2023. http://dx.doi.org/10.22617/brf230334-2.
Texte intégralRésumé :
Drawing on 2023 survey results, this brief analyzes the widening global trade finance gap, shows why higher financing costs are posing a challenge to companies, and assesses the shift toward trade digitalization and sustainable finance. Based on responses from hundreds of banks and corporates worldwide, it assesses supply chain issues, and shows how credit tightening and geopolitical uncertainty are affecting bank trade finance portfolios. It recommends ways to push forward the global digitalization agenda, harmonize sustainability standards, and expand capacity to help attract new pools of capital, drive financing to small and medium-sized enterprises, and narrow the trade finance gap.
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Collett, Clementine, Gina Neff et Livia Gouvea. The Effects of AI on the Working Lives of Women. Inter-American Development Bank, mars 2022. http://dx.doi.org/10.18235/0004055.
Texte intégralRésumé :
Globally, studies show that women in the labor force are paid less, hold fewer senior positions and participate less in science, technology, engineering and mathematics (STEM) fields. A 2019 UNESCO report found that women represent only 29% of science R&D positions globally and are already 25% less likely than men to know how to leverage digital technology for basic uses. As the use and development of Artificial Intelligence (AI) continues to mature, its time to ask: What will tomorrows labor market look like for women? Are we effectively harnessing the power of AI to narrow gender equality gaps, or are we letting these gaps perpetuate, or even worse, widen? This collaboration between UNESCO, the Inter-American Development Bank (IDB) and the Organisation for Economic Co-operation and Development (OECD) examines the effects of the use of AI on the working lives of women. By closely following the major stages of the workforce lifecycle from job requirements, to hiring to career progression and upskilling within the workplace - this joint report is a thorough introduction to issues related gender and AI and hopes to foster important conversations about womens equality in the future of work.
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VanZomeren, Christine, Kevin Philley, Nia Hurst et Jacob Berkowitz. Wildrice (Zizania palustris ; Manoomin) biology, functions and values, and soil physiochemical properties affecting production : a review of available literature. Engineer Research and Development Center (U.S.), août 2023. http://dx.doi.org/10.21079/11681/47513.
Texte intégralRésumé :
Wildrice (Zizania palustris L.) is an annual aquatic emergent plant primarily distributed across portions of Minnesota, Wisconsin, Michigan, and Canada. Wildrice requires narrow environmental conditions that vary throughout its life cycle. Environmental conditions required include water levels between 15 and 90 cm, slow flowing water, anaerobic soil, and circum-neutral pH. Wildrice production and abundance is most often limited by nitrogen availability. Both short- and long-term changes in local conditions impact distribution and abundance of wildrice at local and regional scales. Reported declines in wildrice production have increased interest in evaluating changing environmental conditions, specifically within the Upper Peninsula of Michigan. Wildrice, or manoomin, is an important food and cultural resource, and remains important to native peoples throughout the region, including the Lac Vieux Desert Band of Lake Superior Chippewa Indians. This report provides a review of literature related to wildrice and examines potential factors affecting its production in the Upper Peninsula of Michigan. This report highlights cultural and traditional values, functions and values of wildrice, and unique chemical and physical aspects of the environment where wildrice grow. Additionally, this report synthesizes the data gathered in the literature review, identifies knowledge gaps, and provides research opportunities for improved wildrice production in the Great Lakes region.