Dissertations / Theses on the topic 'Énergie de la bande interdite'
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Jacopin, Gwenolé. "Nanofils de semiconducteurs à grande énergie de bande interdite pour des applications optoélectroniques." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00746091.
El, Kholdi El Mostafa. "Contribution à l'étude des propriétés magnétiques et de transport d'un nouveau semiconducteur semimagnétique à bande interdite de largeur nulle Hg1-xCoxSe." Montpellier 2, 1993. http://www.theses.fr/1993MON20126.
Morais, Andrade Pedro Henrique. "Interactions hôte-invité entre l'iode gazeux et les matériaux de type MOF : dynamique et réactivité." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR094.
This work describes the synthesis and properties of three families of MOF materials (UiO-6x, MIL-125, CAU-1) used to trap iodine molecules. A first study investigates charge transfer complexes between iodine molecules and MOF frameworks upon adsorption, finding that hafnium-based UiO-66 compounds showed enhanced iodine uptake and transformation into I3-. In this case, a mechanism involving electron transfer from the organic linker to iodine was proposed. Using single crystals of UiO-67(Zr,Hf)_NH2 and taking advantage of Raman resonance effect, the higher stability of the I3- species was put forward by performing Raman mapping. Crystal size was shown to significantly affect iodine adsorption kinetics. In comparison to their aluminum-based structural analogue, MIL-125(Ti) and MIL-125(Ti)_NH2 MOFs demonstrated faster iodine adsorption kinetics due to efficient charge separation. In this case, thermal desorption experiments showed the stability of I3- species, particularly in the presence of -NH2 groups. Moreover, contrary to what is observed for zirconium and hafnium-based MOFs, the influence of titanium in the adsorption and reduction mechanism of I2 is highlighted through a change of the Ti4+ cations' oxidation state. As the band gap energy of MOF materials exhibited an effect over the charge transfer complexes involved in the reaction mechanism for different I2@MOF systems, a combination of methodologies was proposed to determine band gap energies and types using only diffuse reflectance UV-Vis data. The study emphasizes how confinement in porous materials can alter properties and stabilization mechanisms, influencing adsorption and reactivity
Loucif, Abdelhalim. "Caractérisation photoélectrochimique des oxydes formés sur alliages base nickel en milieu primaire des réacteurs à eau pressurisée." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00842998.
Raymond, Stéphane. "Excitations de basse énergie dans les fermions lourds par diffusion inélastique des neutrons." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10103.
Sall, Mamour. "Irradiation par des ions de grande énergie de semiconducteurs III-N (AlN, GaN, InN) : création de défauts ponctuels et étendus." Phd thesis, Université de Caen, 2013. http://tel.archives-ouvertes.fr/tel-00936879.
Mafouana, Rodrigue Roland. "Elaboration des matériaux à bande interdite photonique." Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/MAFOUANA_Rodrigue_Roland_2006.pdf.
The first phase of the project was the development of the opals, particularly the preparation of colloid suspensions by the Stöber reaction. To achieve self-organization of the silica particles with a good quality, we worked on the refinement of the size distribution of the silica particles. We showed that, for our operational device, it is necessary for the reagents to be purified and moderated at 40°C then that the reaction is carried out under moderate agitation (500 tr. Min-1). The colloidal suspensions are stabilized by extraction of the particles and handing-over in suspension in water then by heating with 120°/30 min. The colloidal spheres internal structure shows nanoporosity. The opals were worked out by electrosedimentation and were consolidated at 950°C. The optimal optical properties, maximum reflectivity, were obtained for a 4 hours annealing. The second part of this work consisted in using the silica opal as preforms to infiltrate the porous network and to build inverse opals more promising in term of photonic crystals. We infiltrated the previous opals with materials having a strong index (TiO2, ZrO2, magnetics metals, Au) either by successive infiltrations cycles or by electrocrystallization. The second method gave the most satisfying results. The third part of this work is related to the development of a method to elaborate photonic crystal by depositing successive monolayers of silica particles. On a substrate good quality monolayers were obtained with colloidal suspensions containing between 5. 5 and 9 M of silica in the form of particles of approximately 300 nm and a speed of extraction of 11,5 mm. Min-1. These two-dimensional meta-crystals of hexagonal symmetry show a good of diffraction yield. On the other hand the quality of the following layers degrades quickly. The mechanical stability and great structure quality of the monolayer of silica balls on these substrates made possible their use for the 2D nanostructuration of metal studs and the realization of the DFB laser
Mafouana, Rodrigue Roland Estournes Claude Rehspringer Jean-Luc. "Elaboration des matériaux à bande interdite photonique." Strasbourg : Université Louis Pasteur, 2006. http://eprints-scd-ulp.u-strasbg.fr:8080/531/01/MAFOUANA2006.pdf.
Chauvet-Guibert, Catherine. "Croissance et caractérisation d'hétérostructures ZnBeSe à large bande interdite." Nice, 2001. http://www.theses.fr/2001NICE5596.
Recently, a new family of II-VI wide band gap compounds which is the Be chalcogenides came under focus. These materials are interesting for several reasons. They exhibit a high covalence bonding, which could be positive for increasing the life time of devices based on these materials. Zn(Mg)BeSe allows can also be grown lattice-matched to several commercial substrates like GaAs, Si, GaP. Furthermore, very few experimental data are available on Be-Compounds. Thus the study of BeX physical properties is of fundamental interest. This work deals more particularly with the growth and characterization of ZnBeSe heterostructures. In order to achieve a good epitaxy of ZnBeSe onto silicon, we have shown that the main difdficulty is the reactivity between the components at the interface. We have always obtained a 3D nucleation even for a lattice-matched alloy, which is probably due to a strong affinity between Si and Se. Afterwards, we have realized the first growth of ZnBeSe on GaP substrate. We have achieved a much better crystalline quality than onto Silicon. Finally, we have studied the physical properties of ZnBeSe ternary alloys. The variations of the direct gap have been measured for the first time over the whole composition. This allows to evidence the position of the direct to indirect gap cross-over in the alloy at 46% Be. Phonon LO and TO energies has also been determined by Raman spectroscopy
Pointereau, Elisa. "Etude d’antennes à bande interdite électromagnétique omnidirectionnelles en azimut." Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/ea821a8e-a360-4ebf-820d-e7199f62be6e/blobholder:0/2007LIMO4013.pdf.
This thesis, managed with the RADIALL group, is dedicated to the study of base station antennas conceived with electromagnetic band gap (EBG) materials. These structures boast an omnidirectional radiation pattern in the azimuth plane with a high gain. Two structures have been considered: the cylindrical antenna and the coaxial antenna with a metallic center core. After having presented the sources of excitation as well as dielectric and metallic EBG materials, abacuses have been purposed to facilitate the design. Performances improvement techniques made it possible to increase the directivity, to widen the radiation bandwidth and finally to match the antennas. Two antenna prototypes have been realized. The experimental performances have then been compared to a competitive technology: dipole arrays. Lastly, other polarizations have been studied. An antenna in horizontal polarization has been realized which measurement successfully confirmed the theoretical functioning. Double polarization and circular polarization have only been simulated due to the structure complexity
Moustafa, Lina. "Conception d'antennes à Bande Interdite Electromagnétique large bande et multibandes à base de métasurfaces." Limoges, 2009. https://aurore.unilim.fr/theses/nxfile/default/0b6d599a-f2a9-4deb-b823-5dba8a5d5130/blobholder:0/2009LIMO4027.pdf.
This PhD thesis is dedicated to the study of Electromagnetic Band Gap antennas based on metasurfaces. Metasurfaces are employed in the antenna design to correct the usual limitations of the technology and more precisely to enlarge the banwidth. The possibilities offered by combining partially reflecting surfaces, with respect to structure height are explored. Multi-band and broadband EBG antennas with structured interface are designed. An experimental validation of the wideband antenna concept based on metasurfaces is realized. Finally, it is demonstrated that the product gain-bandwidth of such an antenna can be further improved by the use of a multiple feeding sources system
Poilasne, Gregory. "Antennes et materiaux a bande interdite photonique (b. I. P. )." Rennes 1, 1999. http://www.theses.fr/1999REN10070.
Fedichkin, Fedor. "Excitons indirects dans les puits quantiques de la grande bande interdite." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT324/document.
This thesis is devoted to experimental study of excitons in polar quantum wells(QWs) based on wide band-gap semiconductors. Due to wurtzite crystal structureof these materials, electron and hole are separated in the QW growth axis, sothat excitons can be considered as indirect excitons (IX), a family of long-living bosonic quasi-particles with dipole moment oriented along the QW growth axis. IX are considered as a model system for studies of collective states in quantum gases of bosons, and are also promising for the development of excitonic circuit devices. Long lifetimes and dipole repulsion allow IXs to travel over large distances before recombination providing the opportunity to study exciton transport by optical imaging. In this thesis we address IX transport in a set of GaN/(Al,Ga)N and ZnO/(Mg,Zn)O QWs. This choice of IX is motivated by high binding energy, and potential stability up to room temperature, but present a number of experimental challenges, including (i) dramatic dependence of the exciton radiative lifetime on the exciton density that makes exciton density measurement very complex, (ii) thermally activated nonradiative recombination that quenches exciton PL at room temperature,(iii) coexistence of photon propagation with exciton propagation along the QW plane, and strong inhomogeneous broadening of the exciton emission due to strong built-in electric field and the presence of both monolayeructuations of the QW thickness and the fluctuations of alloy composition in the barriers. We have addressed all these issues and demonstrated exciton propagation by combining continuous wave µ-photoluminescence and time-resolved spectroscopy measurements, supplemented by modelling of the exciton transport within drift-diffusion formalism. In the best quality GaN/(Al,Ga)N QWs grown on free-standing GaN substrates we achieved room-temperature propagation over ~10 µm and up to 20 µm at 4 K. Our results suggest that propagation of excitons under continuous-wave excitation is assisted by effcient screening of the in-plane disorder. Nevertheless, exciton propagation is still limited by the exciton scattering on defects rather than by exciton-exciton scatteringso that improving interface quality can boost exciton transport further
Roncière, Olivier. "Antennes à bande interdite électromagnétique et à cavité fabry-perot reconfigurables." Rennes 1, 2007. http://www.theses.fr/2007REN1S042.
This work is dedicated to the study of Electromagnetic Band Gap (EBG) resonators antennas. It is divided in two parts: the first one deals with the principle of operation of such antennas and the second one describes three examples of reconfigurable EBG resonators. First, the context of the work is highlighted by a detailed state of art on periodic materials. Then, chapter II presents a physical study of EBG resonators. In chapter III, a synthesis methodology of EBG resonator fed by planar array is described. Chapter IV deals with reduced-size structures and highlights major differences with the infinite case. Finally, chapter V presents three examples of reconfigurable EBG antennas. The first one is a dual-polarized, dual-directive structure. The second one radiates a beam whose directivity is controllable and the last one investigates the possibilities of beam scanning offered by a EBG resonator with a high impedance surface
Ferrand, Patrick. "Structures guidantes à bande interdite photonique à base de silicium nanoporeux." Phd thesis, Université Joseph Fourier (Grenoble), 2001. http://tel.archives-ouvertes.fr/tel-00003341.
Ferrand, Patrick. "Structures guidantes à bande interdite photonique à base de silicium nanoporeux." Phd thesis, Université Joseph Fourier (Grenoble ; 1971-2015), 2001. http://www.theses.fr/2001GRE10104.
Said, Aurore. "Matériaux Nanohybrides à Large Bande Interdite: Études de Synthèses, Propriétés et Applications." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2007. http://tel.archives-ouvertes.fr/tel-00266833.
Marko, Hakim. "Développement de dispositifs photovoltaïques à base de CIGSe à grande bande interdite." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0003.
The goal of this work is to improve the understanding of the experimental suboptimal electrical properties of solar cells based on large bandgap Cu(ln,Ga)Se2 (ClGSe), Le. EG > 1,2 eV and gallium content (xGa=[Ga]/([ln]+[Ga])) higher than 30 %. Ln order to try to answer to the problematic, the work have been focused, firstly, on the implementation of large bandgap ClGSe growth processes by thermal coevaporation and, secondly, on the development of CdS alternative buffer layer based on Zn(O,S) grown by atomic layer de position (AL D, in collaboration with the Uppsala University in Sweden) and reactive sputtering. At high Ga content (xGa rv 50 %), the ClGSe growth and its copper composition seems to be key factors for improving solar cells efficiencies. A model has been proposed in order to better understand the copper content effect at high gallium composition. The adjustment of the Zn(O,S) recipe grown by ALD allowed maximizing devices efficiencies close to 15 %. It is suggested that the control of the Zn(O,S) layer led to the favourable conduction band matching at the interface with the CIGSe. The Zn(O,S) de position by reactive sputtering showed a relative harmlessness for the CIGSe surface
JEANROT, JEROME. "Non-linearites optiques dans des semiconducteurs a faible largeur de bande interdite." Paris 11, 1996. http://www.theses.fr/1996PA112066.
Pialat, Elodie. "Le Micro-usinage de dispositifs polymères à bande interdite photonique par faisceau d'ions." Limoges, 2004. http://aurore.unilim.fr/theses/nxfile/default/221048f5-8cc4-493d-9156-e51b053adce6/blobholder:0/2004LIMO0010.pdf.
. The increase in the data transmission traffic imposes innovations. A solution considered is the Wavelenght Demultiplexing Method (WDM) Devices with photonic band gap lend themselves advantageously to the implementation of this technique, since they do not require any consumption of energy. Their manufacture in polymeric technology is the subject of this study. The first part of this work gives a progress report on the bands structures and on the electronic Valence Band Density Of State (VBDOS) of the organic materials use. The following part is devoted to comprehension of the physical phenomena related to the concept of crystal photonic, according to the models of : Yablonovitch and John. Then the theory of the plane waves expansion is developped and used to compute the photonic band gap structures. The 4th part is about the calculation and the manufacture of a focused ion beam machine, with a minimum beam diameter of 10nm, used to etch polymers. The last part exposes the conditions to etch 2D diffractive lattice in PMMA and CR39 according to the previously calculated dimensions
Viale, Pierre. "Gestion des effets non linéaires dans les fibres optiques à bande interdite photonique." Limoges, 2006. http://aurore.unilim.fr/theses/nxfile/default/9a9c89be-3d7c-4b1d-8644-ee484619e0db/blobholder:0/2006LIMO0057.pdf.
Nonlinear effects in optical fibres were managed by means of photonic crystals (PC). On the one hand, such a metamaterial was employed to increase the threshold of appearance of nonlinear effects. Hence a silica core PC fibre exhibiting a large effective mode area was designed and fabricated. The subsequent characterization was studied in detail. Moreover, a properly designed PC allows propagation of light in a low index media such as air, which is a low nonlinear medium. Modelling of hollow core PC fibre was exposed together with our realizations and characterisations. On the other hand, specific properties of PC allow to propagate light in a highly-nonlinear low-index liquid filling the hollow core of a PC fibre so as to exacerbating nonlinear effects and creating novel optical sources. To the best of our knowledge, a low-loss liquid-core PC fibre was fabricated for the first time. A comprehensive theory of propagation was developed and confirmed by experiments
Jaffré, Tanguy. "Caractérisation des matériaux à bande interdite électromagnétique multiperiodiques et leurs applications aux antennes." Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/342540ff-1e0d-4bdb-8afb-23771b268d27/blobholder:0/2005LIMO0004.pdf.
3-D dielectric or metallic Electromagnetic BandGap (EBG) materials allow interesting properties in spatial and frequency filtering. One of the most difficult things in this domain is to realize it. The rapid prototyping offers a solution. A part is built layer by layer. An UV laser comes to polymerize a paste composed of ceramic and photosensitive resin. The ceramic, after sintering, has the same properties than those obtained through traditional manufacturing processes. The purpose of this report is to characterize this kind of materials by using their own electromagnetic properties. A bench of measurement in free space is used to identify the bandgap over a large frequency range of the manufactured structures. EBG antennas are realized from the manufactured and characterized 3-D electromagnetic bandgap materials. The filtering of the spatial and frequency wave obtained with those materials allowscontrolling the radiation directions and the directivity of the antenna
DAGUZAN, PHILIPPE. "Dynamique ultra-rapide des porteurs photoexcites dans les solides a grande bande interdite." Paris 6, 1996. http://www.theses.fr/1996PA066106.
Sérier, Cédric. "Conception, réalisation et caractérisation d'antenne à bande interdite photonique : application au fort gain." Limoges, 2002. http://www.theses.fr/2002LIMO0017.
This report is a study on photonic crystals, in order to use their properties to ceate P. B. G. Resonator antennas : Wideband 1D P. B. G. Resonator antenna : High gain 1D P. B. G. Resonator antenna : 3D P. B. G. Resonator antenna. More precisely, the different steps to design such antennas are presented as well as a study on the excitation of the structure by slot, which can replace patch antenna excitation
Elayachi, Moussa. "Structures à bande interdite électromagnétique : étude et réalisation pour la miniaturisation des antennes." Nice, 2008. http://www.theses.fr/2008NICE4069.
The works presented in this thesis concern the study of printed antennas using EBG materials. In a first part, we presented the identification methods of band gap of the EBG materials. We detailed the Method of Reflection Phase used in this work. We also presented the EBG prototypes developped according a “Mushroom type” design. In the second part, we studied the electromagnetic behavior of a printed reference antenna, using PEC ground plane, which has excellent characteristics of radiation. The EBG structures designed and employed like PMC ground planes, allow to miniaturize considerably the total thickness of the antenna. This study also enabled to highlight that EBG materials would be able to constitute a way towards the design of the multi bands and/or ultra wide band antennas. In the last part, we presented an original EBG structure which was optimized so as to be more competitive in terms of costs and performances compared with the Mushroom structure. This new EBG structure enables to design planar low profile antenna, whose the measured performances are almost as good as that the reference antenna performances. The developed planar antenna offers interesting prospects for the Wireless applications (WIFI, WIMAX, …)
Cheype, Cyril. "Etude et utilisation des propriétés des matériaux BIPs à défaut pour la conception d'antennes." Limoges, 2001. http://www.theses.fr/2001LIMO0017.
Sincie few years, the Photonic Band Gap structure study is in considerable extension. Numerous applications has been made in optical frequencies as well as in microwave frequency range for the design of filter or antenna devices. This report presents a description of the electromagnetic characteristics of the Photonic Band Gap materials. We particularly focus on the PBG materials with defects
Bichelot, François. "Technique d'amélioration de la bande passante en directivité et de l'efficacité de surface des antennes a bande interdite électromagnétique (BIE)." Rennes, INSA, 2007. http://www.theses.fr/2007ISAR0023.
Electromagnetic bandcap (EBG) antennas are an interesting lead, provinding high directivity and good copactedness. Nevertheless, those structures suffer from a narrow directivity bandwidth and a low efficency when lateral dimensions are reduced. In order to improve the directivity bandwidth and the efficiency of EBG resonators, several techniques are proposed in this PHD dissertation. The first part of this study deals with the use of a multilayer frequency selective surfaces structure in order to build a multiresonant and widened directivity badwidth resonator. The second part of the study is dedicated to the improvement of the efficiency. This part is focused on a dielectric resonator antenna and an EBG resonator, different shieldings are investigated. Results have highlighted a high efficiency
Zhao, Hongming. "Étude experimentale de la propriété de couplage spin-orbite dans des structures semi-conductrices de basse dimensionalité." Grenoble, 2010. http://www.theses.fr/2010GRENY028.
We have studied the spin-orbit coupling and optical properties in severallow-dimensional semiconductor structures. First, the spin dynamics in (001) GaAs/A/GaAs two-dimensional electron gas was investigated by time resolved Kerr rotation technique under a transverse magnetic field. The in-plane spin lifetime is found to be anisotropic. The results show that the electron density in two-dimensional electron gas channel strongly affects the Rashba spin-orbit coupling. Then, a large anisotropy of the magnitude of in-plane conduction electron 9 factor in asymmetric (001) GaAs/AIGaAs QWs was observed and its tendency of temperature dependence was studied. Second, the experimental study of the in-plane-orientation dependent spin splitting in the C(0001) GaN/A/GaN two-dimensional electron gas at room temperature was reported. The measurement of circular photogalvanic effect current clearly shows the isotropic in-p/ane spin splitting in this system for the first time. Third, the first measurement of conduction electron 9 factor in GaAsN at room temperature was done by using time resolved Kerr rotation technique. It demonstrates that the 9 factor can be modified drastically by introducing a small amount of nitrogen in GaAs bulk. Finally, the optical characteristic a indirect type Il transition in a series of size and shape-controlled linear CdTe/CdSe/CdTe heterostructure nanorods was studied by steady-state and time resolved photoluminescence. Our results show the steady transfer from the direct optical transition (type 1) within Cd Se to the indirect transition (type Il) between CdSe/CdTe a the length of the nanorods increases
Stanowski, Radoslaw Wojciech. "Nano-ingéniérie de bande interdite des semiconducteurs quantiques par recuit thermique rapide au laser." Thèse, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/1960.
Ibnouelghazi, Elalami. "Étude de l'interaction d'échange dans les semiconducteurs semimagnétiques à faible largeur de bande interdite." Montpellier 2, 1986. http://www.theses.fr/1986MON20125.
DIB, MOHAMED. "Structure electronique au voisinage de la bande interdite des nanocristaux de cdse et cds." Paris 7, 1999. http://www.theses.fr/1999PA077073.
Fehrembach, Anne-Laure. "Réseaux résonnants à Bande Interdite Photonique, nouveaux filtres pour le D. W. D. M." Aix-Marseille 3, 2003. http://www.theses.fr/2003AIX30028.
Dense wavelength division multiplexing (D. W. D. M. ) significantly increases the optical telecommunication transmission rates. To separate the channels, narrow band spectral filters are necessary. Resonant gratings, composed with a grating engraved on a planar waveguide, are a potential solution. These structures support eigenmodes, which can be excited by a wave coming out of an optical fiber. The excitation creates a resonance peak in the reflected beam, for a given wavelength and incidence angle. In general, the peak does not exhibit the qualities required for the D. W. D. M. : at oblique incidence, the angular and spectral tolerances are weak, and the line shapes are polarization dependent. Combining photonic crystals concepts, a rigorous phenomenological theory, and a perturbative theory, we design a filter that meet all the conditions imposed by the D. W. D. M.
Ibnouelghazi, Elalami. "Etude de l'interaction d'échange dans les semiconducteurs semimagnétiques à faible largeur de bande interdite." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37598429t.
Elbaz, Anas. "Sources laser compatibles silicium à base de Ge et GeSn à bande interdite directe." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS077/document.
Silicon photonics is experiencing a very important development. The laser source integration is a very important issue in silicon photonics. Currently, these sources are obtained with type III-V semiconductors on GaAs or InP substrates. Their integration in a silicon industry is delicate and above all does not allow to take full advantage of a CMOS environment.The integration of a monolithically optical source represents an important challenge. The elements of column IV (Si, Ge) are indirect bandgap semiconductors, with low radiative recombination efficiency, and therefore are not good candidates. However, a paradigm shift is underway with the recent demonstration that it was possible to manipulate the band structure of germanium-based semiconductors to direct bandgap, i.e. transform them into efficient transmitters. This engineering can be achieved either by using external tensors such as silicon nitride or by making alloys with tin (GeSn), or by combining both. This thesis deals with the study of these direct bandgap semiconductors. The goal will be to demonstrate a laser with this new type of materials
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.
Mercury 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
Vu, Thai-Hung. "Antenne à bande interdite électromagnetique (B. I. E. ) directive : contribution à l’élargissement de la bande passante et à l’évaluation de l’impédance." Rennes 1, 2009. http://www.theses.fr/2009REN1S033.
This thesis focuses on the directive EBG (Electromagnetic Band Gap) and FP (Fabry-Pérot) antennas and tries to solve their two major problems: i) the difficulty of the evaluation and matching of their impedance, and ii) their narrow directivity bandwidth. After a brief state of the art in chapter I on the EBG structures as well as on their applications in microwave devices and antennas, chapter II presents the design aspects of the FP and EBG antennas. Chapter III proposes an original theoretical method to enable the evaluation of the input impedance of these antennas. To this end, a “modified image method” is proposed which transforms this subject to that of an antenna array composed of appropriately weighted primary sources. This model allows the evaluation of the input impedance by using the mutual coupling matrice. The resulting method is then used to match the input impedance of an FP cavity antenna excited by a simple dipole source. Chapter IV is devoted to the study of a combined PRS (Partially Reflecting Surface) composed of two or several single PRSs. This new structure shows a non conventional property: the phase of its reflection coefficient is an increasing function versus frequency. Chapter V uses this unusual property of the combined PRS to enlarge the bandwidth of the EBG antennas. An optimization process based on the Genetic Algorithm is set up to maximise the directivity bandwidth of FP antenna associated with a combined PRS. Finally, an example of realization is presented to confirm the theoretical results and the design procedure
Vigué, Florence. "Optoélectronique visible et ultraviolette à base de semi-conducteurs II-VI à large bande interdite." Nice, 2001. http://www.theses.fr/2001NICE5632.
Over the past few years, there has been a great deal of work focused on wide bandgap semiconductors for their applications in electronics and optoelectronics. Main goals are the fabrication of ultraviolet (UV) photodetectors and blue and UV laser diodes. In this work, II-VI compounds based on zinc selenide (ZnSe) and zinc oxyde (ZnO) are studied for these purposes. UV photodetectors based on ZnSe and especially on (Zn,Mg,Be,Se) quaternary alloys are first reported. Three types of structures have been studied which are p-i-n, Schottky barrier and metal-semiconductor-metal photodiodes. With these different devices, high maximum spectral responses, important UV/visible contrasts and low noise levels are achieved. This work thus demonstrates the potential of ZnSe and (Zn,Mg,Be,Se) compounds for UV detection. Growth of ZnO on sapphire substrate has also been studied. It is demonstrated that two different growth modes can be achieved depending on experimental conditions. Two-dimensional growth mode layers exhibit a mosaic structure with columnar subgrains delineated by vertical dislocations whereas the three-dimensional growth mode generates numerous interactions between dislocations and leads to higher structural quality films. A total dislocation density of 3-5x109 cm-2 is obtained in that case
Raboin, Jean-Christophe. "Complexes de métaux de transition pour la photosensibilisation de semi-conducteurs à large bande interdite." Metz, 1999. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1999/Raboin.Jean_Christophe.SMZ9940.pdf.
Ridaoui, Mohamed. "Fabrication et caractérisation de MOSFET III-V à faible bande interdite et canal ultra mince." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11118.
Abstract : Silicon-based devices dominate the semiconductor industry because of the low cost of this material, its technology availability and maturity. However, silicon has physical limitations, in terms of mobility and saturation velocity of the carriers, which limit its use in the high frequency applications and low supply voltage i.e. power consumption, in CMOS technology. Therefore, III-V materials like InGaAs and InAs are good candidates because of the excellent electron mobility of bulk materials (from 5000 to 40.000 cm2 /V.s) and the high electron saturation velocity. We have fabricated ultra-thin body (UTB) InAs/InGaAs MOSFET with gate length of 150 nm. The frequency response and ON-current of the presented MOSFETs is measured and found to have comparable performances to the existing state of the art MOSFETs as reported by the other research groups. The UTB MOSFETs were fabricated by self-aligned method. Two thin body conduction channels were explored, In0,75Ga0,25As and a composite InAs/In0,53Ga0,47As. A thin upper barrier layer consisting of InP (3nm) is inserted between the channel and the oxide layers to realized a buried channel. Finally, the Al2O3 (4 nm) was deposited by the atomic layer deposition (ALD) technique. It is well known that the source and drain (S/D) contact resistances of InAs MOSFETs influence the devices performances. Therefore, in our ultra-thin body (UTB) InAs MOSFETs design, we have engineered the contacts to achieve good ohmic contact resistances. Indeed, for this UTB architecture the use of ion implantation technique is incompatible with a low thermal budget and cannot allow to obtain low resistive contacts. To overcome this limitation, an adapted technological approach to define ohmic contacts is presented. To that end, we chose low thermal budget (250°C) silicide-like technology based on Nickel metal. Finally, we have studied and analyzed the resistance of the alloy between Nickel and III-V (Rsheet). MOSFET with two different epilayer structures (In0,75Ga0,25As and a composite InAs/In0,53Ga0,47As) were fabricated with a gate length (LG) of 150 nm. There were few difference of electrical performance of these two devices. We obtained a maximum drain current (ION) of 730 mA/mm, and the extrinsic transconductance (GM, MAX) showed a peak value of 500 mS/mm. The devices exhibited a current gain cutoff frequency fT of 100 GHz and maximum oscillation frequency fmax of 60 GHz for drain to source voltage (VDS) of 0.7 V.
Laurent, Stéphane. "Cavités à bande interdite photonique bidimensionnelle et application à une source de photons uniques indiscernables." Paris 6, 2006. http://www.theses.fr/2006PA066535.
Isolating a single self-assembled InAs/GaAs quantum dot is a way to produce single photons. Moreover, the successively emitted photons can be indistinguishable if the emission process happens sufficiently fast. This radiative lifetime shortening can be obtained by the use of cavity effects (Purcell effect). In this work we describe the development of two-dimensional photonic band gap cavities for that purpose. A first step was the fabrication of GaAs photonic crystal cavities. Then, inserting a single layer of InAs/GaAs quantum dots in the structure, we managed to isolate a single quantum dot coupled to a single cavity mode, in the weak coupling regime. This system is an indistinguishable single photon source, with a degree of photon indistinguishability of 70 %. The observation of the photon indistinguishability is only possible through a shortening of the emitter lifetime, and indicates that the Purcell effect is more than 25 in this system
Rault, Gabriel. "Verres à basse énergie de phonon pour l'amplification optique large bande." Rennes 1, 2001. http://www.theses.fr/2001REN10056.
Lo, Juslan. "Étude de la reconfigurabilité d'une structure à bande interdite électromagnétique (BIE) métallique par plasmas de décharge." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00713274.
Korytov, Maxim. "Etude des nanostructures de semi-conducteurs à large bande interdite par Microscopie électronique en Transmission quantitative." Phd thesis, Université de Nice Sophia-Antipolis, 2010. http://tel.archives-ouvertes.fr/tel-00520605.
Forster, Simon. "Nouveau matériau semi-conducteur à large bande interdite à base de carbures ternaires - Enquête sur Al4SiC4." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI095.
Wide bandgap semiconductor materials are able to withstand harsh environments and operate over a wide range of temperatures. These make them ideal for many applications such as sensors, high-power and radio-frequencies to name a few.However, more novel materials are required to achieve significant power efficiency of various applications or to develop new applications to complement current wide bandgap semiconductors such as GaN and SiC.In this dissertation, three different methods are used to study one of these novelmaterials, aluminium silicon carbide (Al4SiC4): (1) ensemble Monte Carlo simulationsin order to study the electron transport properties of the novel ternary carbide, (2)experimental studies to determine its material properties, and (3) device simulationsof a heterostructure device made possible by this ternary carbide. All these methodsinterlink with each other. Data from each of them can feed into the other to acquire newresults or refine obtained results thus leading way to attractive electrical properties such as a bandgap of 2.78 eV or a peak drift velocity of 1.35×10 cm s .Ensemble Monte Carlo toolbox, developed in-house for simulations of Si, Ge, GaAs,AlxGa1−xAs, AlAs, and InSb; is adopted for simulations of the ternary carbide by adding anew valley transformation to account for the hexagonal structure of Al4SiC4. We predicta peak electron drift velocity of 1.35×107 cms−1 at electric field of 1400 kVcm−1 and a maximum electron mobility of 82.9 cm V s . We have seen a diffusion constant of 2.14 cm2s−1 at a low electric field and of 0.25 cm2s−1 at a high electric field. Finally, weshow that Al4SiC4 has a critical field of 1831 kVcmsemiconductor crystals are used that had previously been grown at IMGP, one by solution grown and the other by crucible melt. Three different experiments are performed on them; (1) UV, IR and Vis Spectroscopy, (2) X-ray Photo Spectroscopy, and (3) Two- and four-probe measurements where metal contact are grown on the crystals. Here we have found a bandgap of 2.78 ± 0.02 eV UV, IR and Vis Spectroscopy and a thick oxide layer on the samples using XPS. Unfortunately the Two- and four-probe measurements failed to give any results other than noise, most likely due to the thick oxide layer that was found on the samples.In the device simulations, a commercial software Atlas by Silvaco is utilized to predict performance of heterostructure devices, with gates lengths of 5 μm, 2 μm and 1 μm, made possible by the ternary carbide in a combination with SiC. The 5 μm gate length SiC/Al4SiC4 heterostructure transistor delivers a maximum drain current of 1.68×10−4 A/μm, which increases to 2.44×10−4 A/μm and 3.50×10−4 A/μm for gate lengths of 2 μm and 1 μm, respectively. The device breakdown voltage is 59.0 V which reduces to 31.0 V and to 18.0 V for the scaled 2 μm and the 1 μm gate length transistors. The scaled down 1 μm gate length device switches faster because of the higher transconductance of6.51×10−5 S/μmcomparedtoonly1.69×10−6 S/μmforthelargestdevice.Finally,a sub-threshold slope of the scaled devices is 197.3 mV/dec, 97.6 mV/dec, and 96.1 mV/dec for gate lengths of 5 μm, 2 μm, and 1 μm, respectively
Chantalat, Régis. "Optimisation d'un réflecteur spatial à couverture cellulaire par l'utilisation d'une antenne à bande interdite électromagnétique multisources." Limoges, 2003. http://aurore.unilim.fr/theses/nxfile/default/37e18543-71c3-4f1f-a746-c37114179db9/blobholder:0/2003LIMO0040.pdf.
This report is dedicated to the optimization of a multibeam parabolic reflector using a multiffed EBG antenna. The horns which are the structures classically placed in the focal plane of the reflector lead to spill over losses or beam crossover losses. The interest of the EBG antenna successively excited by several feeds is to generate on its surface some radiating apertures which have sufficient size allowing the reduction of the spillover losses. These radiating apertures which are at the origin of each beams are interlaced to keep a reduced center to center distance limiting the beam crossover losses. The functioning analysis and a conception mrthod of the antenna with EBG cavity were described during this thesis. A new way of ffeding by waveguide and the bahavior of the EBG antenna with several elementary sources were also studided
Biniek, Laure. "Polymères semi-conducteurs à faible largeur de bande interdite : de la synthèse au dispositif photovoltaïque organique." Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/BINIEK_Laure_2010.pdf.
In the field of organic photovoltaic, conjugated electron donor polymers with improved optoelectronic properties are highly needed. Therefore, that research work is focused on the design and investigation of a new family of donor-acceptor alternating low band-gap copolymers, using 2,1,3-benzothiadiazole as electron-deficient unit, and thieno[3,2-b]thiophene and alkylthiophenes moieties as electron-rich units. By the inclusion of fused thiophene rings we intend to enhance the hole carrier properties. Various alkyl side-chains are introduced onto different positions along the conjugated backbone in order to reach efficient solubility in common organic solvents and simultaneously allow investigations of structure/properties relationships. We have also studied the effect of conjugation length and planarity on the optoelectronic properties. In the first section we discuss the synthesis methods of the monomers which involve several organic and organometallic reactions. Then, the copolymers have been synthesized by Stille or Suzuki cross coupling polycondensation. In the second part, special focus is devoted on how modifications in the conjugated backbone length and conformation (side chains length and positioning, coplanar units) are affecting the related material properties (electrochemical, UV-vis absorption, microstructure and charge carrier mobility). Finally, we have elaborated bulk heterojunction solar cells based on copolymer:C60-PCBM blend and correlated the OPV device performances with the optoelectronic properties of the polymers
Denis, Marie-Sandrine. "Contribution à l'étude des matériaux à Bande Interdite Photonique : Application dans le domaine des antennes imprimées." Limoges, 1998. http://www.theses.fr/1998LIMO0057.
GUENNAN, DRISS. "Emission stimulee et gain optique de semiconducteurs a large bande interdite directe (zns, znse et gan)." Université Louis Pasteur (Strasbourg) (1971-2008), 1998. http://www.theses.fr/1998STR13057.
Martinez, Bertille. "Étude des propriétés optoélectroniques de nanocristaux colloïdaux à faible bande interdite : application à la détection infrarouge." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS254.
Colloidal semiconductor nanocrystals are nanomaterials synthesized in solution. Below a certain size, these nanocrystals acquire quantum confinement properties: their optoelectronic properties depend on the nanoparticle size. In the visible range, colloidal nanocrystals are quite mature. The next objective in this field is to get infrared colloidal nanocrystals. Mercury selenide (HgSe) and mercury telluride (HgTe) are potential candidates. The goal of this PhD work is to strengthen our knowledge on optical, optoelectronic and transport properties of these nanocrystals, in order to design an infrared detector.To do so, we studied the electronic structure of HgSe and HgTe for different sizes and surface chemistries. We can then determine the energies of the electronic levels and the Fermi energy, quantify doping level … We show that the nanocrystal size has an influence on doping level, which gets more and more n-type as the nanocrystal size gets larger. We even observe a semiconductor-metal transition in HgSe nanocrystals as the size is increased. The doping control with surface chemistry is then investigated. By using dipolar effects or oxidizing ligands, we show a doping control over several orders of magnitude. Thanks to these studies, we are able to propose a HgTe based device for detection at 2.5 µm, which structure allows to convert effectively the absorbed photons into an electrical current and to get a high signal over noise ratio. We get a photoresponse of 20 mA/W and a detectivity of 3 × 10 9 Jones
Schreider, Ludovic. "Antennes à très large bande passante et de très faible épaisseur : application à l'intégration d'antennes dans des structures de porteurs dans la bande 100 MHz-1GHz." Paris, ENST, 2006. http://www.theses.fr/2006ENST0040.
One of the major stakes in the integration of new Electronic Warfare (EW) systems into defence carriers is the reduction of the obstruction of antennas. The bandwidth of the antennas which are used in EW applications can be about 10:1 and the lowest frequency can be close to the hundred of MHz, which makes the integration of the antennas very difficult even impossible according to cases. EW antennas are usually placed above an absorbing cavity. The manufacture of absorbing material is today still "handmade" and thus very expensive. Moreover, these materials are heavy and they do not exhibit the same electric characteristics of one manufacture at the other. The work presented in this report is devoted to the realization of wideband antennas with very low thickness and without absorbing material. We proposed and validated a new structure based on Electromagnetic Band Gap substrate. The new structure makes it possible to remove absorbing materials, to reduce the thickness of the antennas and to reduce the manufacturing costs. The new structure has contrary to all other EBG structures the advantage of being ultra broad band and compact (about 1/100th of wavelength thick). We showed the interest to use such a device to reduce the thickness and to improve the performances of the planar antennas of form and unspecified polarization