Tesi sul tema "Semi-conducteur à large bande"
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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.
Testo completoWide 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
Pacuski, Wojciech. "Spectroscopie optique de semi-conducteurs magnétiques dilués à large bande interdite, à base de ZnO et GaN". Phd thesis, Grenoble 1, 2007. http://www.theses.fr/2007GRE10310.
Testo completoThis work presents a magnetooptical study of diluted magnetic semiconductors (DMS) based on ZnO and GaN, doped with manganese, iron, and cobalt. Both host materials, ZnO and GaN, are wide band gap semiconductors with a wurtzite structure, a weak spin-orbit coupling and a strong electron-hole exchange interaction within the excitons. In the presence of a magnetic field, the magnetic ions induce in such materials a giant Zeeman effect with a complex behavior: excitons anti-cross, and not only the transition energies, but also the oscillator strengths are strongly affected by the giant Zeeman effect. On thin epitaxial layers grown on (0001) sapphire, we observed the giant Zeeman splitting of the A and B excitons, which are optically active in the Faraday configuration when the propagating light is parallel to the c-axis. The Zeeman splitting decreases with the temperature and increases non-linearly with the magnetic field, demonstrating a dependence on the magnetization of the localized spins. A quantitative analysis allows us to discuss the detailed behavior of the magnetization and to estimate the p-d exchange integral beta for the studied wide bandgap DMS. For the d^5 electronic configuration (Mn2+, and Fe3+) the magnetization follows a Brillouin function, whereas, for d7 or d4 of Co2+, and Mn3+, respectively, the spin orbit coupling and the trigonal crystal field lead to an anisotropic magnetization, consistent with that deduced independently from the analysis of intra-ionic optical transitions. We find a positive sign of beta for (Ga,Mn)N, and (Ga,Fe)N. In ZnO, the sign of the spin-orbit interaction, which determines the structure of the valence band, has been a matter of debate. Assuming that the valence band ordering in ZnO is Gamma_9, Gamma_7, Gamma_7 (this corresponds to usual, positive sign of the spin-orbit coupling), we find beta to be negative for (Zn,Co)O, and to be close to zero in (Zn,Mn)O. However, assuming the reversed valence band ordering, we find beta to be positive in both ZnO based DMS. The sign and the value of p-d exchange integrals determined from our magnetooptical measurements do not follow material trends in DMS and cannot be explained by models based on the virtual crystal approximation. This suggests that the p-d coupling in wide gap DMS is in the strong coupling regime, so that the nature of the observed giant Zeeman splitting is different from that in classical diluted magnetic semiconductors
Pacuski, Wojciech. "Spectroscopie optique de semi-conducteurs magnétiques dilués à large bande interdite, à base de ZnO et GaN". Phd thesis, Université Joseph Fourier (Grenoble), 2007. http://tel.archives-ouvertes.fr/tel-00296634.
Testo completoOn a mesuré expérimentalement le splitting Zeeman géant des excitons A et B avec des couches epitaxiées sur saphir (0001) et une propagation de la lumiere parallele a l'axe c du cristal et au champ magnétique (configuration Faraday). Le splitting Zeeman géant diminue avec la température et augmente non linéairement avec le champ magnétique en accord avec l'aimantation calculée des spins isolés. Une analyse quantitative nous a permis d'analyser les propriétés magnétiques et de mesurer les intégrales d'échange pour l'ensemble des matériaux étudiés. Pour des ions avec une configuration d5 (Mn2+ et Fe3+), l'aimantation suit une fonction de Brillouin, mais pour les configurations d7 et d4 (Co2+ ou Mn3+) l'interaction spin-orbite et le champ cristallin trigonal induisent une aimantation anisotrope, en accord avec l'analyse des transitions internes des ions mesurées en spectroscopie infrarouge. Pour (Ga,Mn)N, et (Ga,Fe)N, nous avons trouvé un signe positive pour l'intégrale d'échange entre trous et spins localisés (beta). En supposant une symétrie de la bande de valence dans ZnO correspondant a une interaction spin-orbite positive (Gamma_9, Gamma_7, Gamma_7), nous trouvons un signe négative de beta pour (Zn,Co)O, et beta est de pres de zéro pour (Zn,Mn)O. Toutefois, dans l'hypothese avec spin-orbite négative, nous trouvons un signe positif de beta. Les signes et les valeurs des intégrales d'échange déterminées a partir de nos mesures magnéto-optiques ne peuvent pas etre expliqués par des tendances matérielles et des modeles basés sur l'approximation de cristal virtuel. Ceci suggere que l'échange p-d en DMS a large bande interdite, soit dans le régime de couplage fort, et la nature de splitting Zeeman géant observé est différente qu'en semi-conducteurs magnétiques dilués classiques.
Fisne, Christophe. "Métasurfaces actives pour applications large bande". Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0086.
Testo completoMetasurfaces have particular electromagnetic properties such as unusually refractive index, electromagnetic band gap and high impedance surface. Also named Artificial Magnetic Conductor (AMC), they are a focus of interest in the antennas field. Indeed, greater isolation between radiating elements and miniaturization of antenna with reflective plan can be achieved with those structures. Although they suffer from poor bandwidth (less than 10%), which make them inconsistent with wideband applications. To overcome this frequency limitation, implementation of non-Foster active circuits paves the way to extend the bandwidth of high impedance surfaces. In this respect, the thesis goal is to conceive a wideband high-impedance reflector with the integration of non-Foster circuits. The aimed bandwidth is [0.5 GHz; 1.5 GHz], that is to say 100% of the relative bandwidth. In this thesis, a synthesis methodology to realize a wideband AMC is proposed: an AMC reflector under normal incidence is conceived from a metasurface connected to a non-Foster circuit. The circuit is loaded with an optimized impedance. Analytic relationships between the reflection coefficient and the load impedance of the non-Foster circuit are given. Firstly, a metasurface working with linear polarizations and where the connection of the non-Foster circuit is offset. This topology protects the circuit against the perturbations due to the incident electromagnetic waves. Moreover, a study to extend metasurface functioning to circular polarization is under way. Then, a non-Foster circuit of type Negative Impedance Converter (NIC) is designed. A particular topology of circuit is selected in order to simplify the realization. It has been conceived using only components “off-the-shelf” and potentiometers which control the input impedance. Finally, the circuits load is calculated to obtain the attended wideband AMC behavior according with the real performance of the non-Foster circuit
Bouffaron, Renaud. "Modélisation et Réalisation de Réseaux Sub-Longueur d'Onde :Application au Contrôle de la Réflectivité Large Bande, Large Incidence". Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2008. http://tel.archives-ouvertes.fr/tel-00353626.
Testo completoRegnat, Guillaume. "Onduleur à forte intégration utilisant des semi-conducteurs à grand gap". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT050/document.
Testo completoWide-band-gap (WBG) semiconductors (SiC and Gan) offer interesting characteristics to realize high density power electronics converters. Conventional packaging used for silicon devices is no more adapted for those now components. Development of dedicated packaging for WBG devices is absolutely required. This PhD thesis presents a new 3D package based on Printed Circuit Board (PCB) industrial process. The module architecture is based on “Power Chip On Chip” concept which allows reducing electromagnetic perturbations. PCB fabrication process offers high design flexibility in three dimensions and allows removing wire bonding to interconnect power die and package. The power module design process is buit on multi-physics design tools in the aim to quantify electromagnetic and thermal behavior of the module. Furthermore, several optimization parameters are highlighted. A power module prototype, with four commutation cells in parallel based on SiC MOSFET, has been produced thanks to industrial facilities. Tests realized on new power module confirm the validity of the concept but furthermore to highlight critical technological parameters to realize an industrial power module
Grelier, Michael. "Miniaturisation des antennes large bande à l'aide de matériaux artificiels". Phd thesis, Télécom ParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00574620.
Testo completoRaboin, 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.
Testo completoVigué, Florence. "Optoélectronique visible et ultraviolette à base de semi-conducteurs II-VI à large bande interdite". Nice, 2001. http://www.theses.fr/2001NICE5632.
Testo completoOver 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
Kaddour, Darine. "Conception et réalisation de filtres RF passe-bas à structures périodiques et filtres Ultra Large Bande, semi localisés en technologie planaire". Phd thesis, Grenoble 1, 2007. http://www.theses.fr/2007GRE10095.
Testo completoLn recent years, extensive research and development efforts have been put into exploiting planar filters for their potential qualities of low cost, tiny weight and high degree of integration. The aim of the research work presented in this manuscript is the design and the realization of selective and miniaturized planar filters. A new topology of compact low-pass filter with periodic structures, constituted by a transmission line loaded by SMT capacitors, is proposed. A rigorous design method for the low-pass filter is also implemented. The measurements of the low-pass filters, realized ne al' to 1 GHz in a CPW technology, in good agreement with simulations demonstrated interesting electrical proprieties of rejection, matching and spurious suppression. The validity of this topology is also investigated for higher frequencies with the realization of a low-pass filter in the K-band. Several capacitor's characterization approaches were also investigated. The implementation of capacitors in a low pass filter with periodic structure carried out constitutes the most precise way to characterize capacitors. A new topology of Ultra Wide Band band-pass filters, based on the combination of a high pass filter with short circuited stubs and a low pass filter with capacitively loaded lines, is proposed, The measurements of the prototype filters realized in a microstrip teclmology, in good agreement with simulations, show interesting proprieties of selectivity, miniaturization and spurious suppression
Kaddour, Darine. "Conception et Réalisation de filtres RF passe-bas à structures périodiques et filtres Ultra Large Bande, semi-localisés en technologie planaire". Phd thesis, Grenoble 1, 2007. http://tel.archives-ouvertes.fr/tel-00267881.
Testo completoVennegues, Philippe. "Propriétés structurales de films de semi-conducteurs wurtzite hetéroépitaxiés selon des orientations non- et semi-polaires". Habilitation à diriger des recherches, Université de Nice Sophia-Antipolis, 2009. http://tel.archives-ouvertes.fr/tel-00520457.
Testo completoKorytov, 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.
Testo completoMotaweh, Tammam. "Modélisation et validation expérimentale de nouvelles structures SOA large bande et de techniques d'élargissement de la bande passante optique". Thesis, Brest, 2014. http://www.theses.fr/2014BRES0117/document.
Testo completoSOA-based optical amplification became crucial for increasing optical system capacity and to benefit from the broad bandwidth of optical fibers. In this work we present both theoretical and experimental studies for a new broadband SOA developed by Alcatel Thales III-V lab in the framework of AROME and UltraWIDE ANR projects.We developed firstly a semi-phenomenological model for both the material gain and the gain coefficient of a multi-quantum well -based SOA structure with a reduced set of parameters. This material gain model has been integrated in an existing SOA model and proved its performance in reproducing steady state behavior of this new broadband SOA (gain and noise figure) for a wide range of wavelengths, input powers and bias currents. Thanks to this model, we studied the influence of the SOA geometrical structure on the optical bandwidth for a given target gain, by varying length, number of electrodes and bias current. We showed that two-electrode SOA structures do not provide any improvement of the bandwidth compared to the one-electrode case. However, the two-electrode structure allows the optimization of both the SOA saturation power and the noise figure, without sacrificing neither the maximum gain nor the optical bandwidth. We have also shown that for this kind of component, an increase in the injected optical power could be compensated by an increase in the supply current to maintain a wide optical bandwidth.We have also investigated two techniques to widen the optical bandwidth of our broadband SOA. The first one is based on a modification of the SOA structure by introducing a selective reflection filter (ESOA). Its experimental implementation allowed the amplification of an 8-CWDM-channel comb in a bandwidth (defined at -1 dB) of 140 nm. The second one, based on a hybrid Raman-SOA amplifier, provided an optical bandwidth (defined at -1 dB) of 89 nm with a gain of 17 dB. With this last technique, we were able to achieve a 5-CWDM-channel comb transmission up to 10 Gb/s over 100 km
Quaglia, Michael. "Méthodes de prévision acoustique semi-analytiques pour un doublet d'hélices contrarotatives isolé". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC063/document.
Testo completoNo abstract
Quaglia, Michaël. "Méthodes de prévision acoustique semi-analytiques pour un doublet d'hélices contrarotatives isolé". Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11781.
Testo completoDerkowska, Beata. "Contribution à l'étude des propriétés optiques linéaires et non linéaires des semi-conducteurs AIIBVI". Angers, 2001. http://www.theses.fr/2001ANGE0003.
Testo completoBouynet, Enmmanuelle. "Propriétés diélectriques large bande de matériaux à basse température : application à l'étude de composés de la famille des fullerènes et de composites isolant-polymère conducteur". Bordeaux 1, 1996. http://www.theses.fr/1996BOR10690.
Testo completoMaertens, Alban. "Etude de la réalisation d'une structure transistor (FET) pour l'observation de l'exciton du ZnO sous champ électrique". Thesis, CentraleSupélec, 2016. http://www.theses.fr/2016SUPL0009/document.
Testo completoThis manuscript covers the design of a field transistor for the observation of photoluminescence of the exciton and the charged excitonic complex of ZnO under the influence of an electric field. For this, simulations have helped to define the specifications of the transistor structure to block the conductivity in the ZnO channel and applying a strong electric field. The second part concerns the choice of gate material and the surface transparent electrode for the observation of photoluminescence in the channel. The gallium oxide (-Ga2O3) was chosen because it has a large gap, insulating properties and semiconductor properties with doping. However, Ga2O3 films doped with Ti, Sn, Zn and Mg MOCVD did not show conductivity. Films of alloys (Ga,Sn)2O3 have not shown either conductivity and their structure is studied intensively. Radio frequency plasma treatment under a flux of argon, oxygen or hydrogen have shown that implantation of hydrogen gives rise to a donor level with 7 meV activation energy. However, the conductivity is modulated by doping Sn and treatments are accompanied by a change of sub-stoichiometry in oxygen, which reduces the transparency due to the formation of deep level of oxygen vacancy. The final structure of the transparent gate in the ultraviolet for the observation of photoluminescence of ZnO can be prepared by a dielectric gate -Ga2O3 and a transparent conductive electrode of (Ga,Sn)2O3 surface treated by a plasma of hydrogen
DOP, SIMON. "Modelisation numerique et caracterisation experimentale d'un simulateur d'ondes electromagnetiques large bande dans une chambre semi-anechoique. Application aux tests en susceptibilite des vehicules automobiles". Paris 6, 1998. http://www.theses.fr/1998PA066748.
Testo completoCHOTARD, RICHARD. "Etude et caracterisation d'un simulateur d'onde electromagnetique large bande en chambre semi-anechoique, facilement modelisable par des codes 3d. Application au test des vehicules automobiles". Paris 6, 1996. http://www.theses.fr/1996PA066831.
Testo completoBenwadih, Mohammed. "Transistors souples et hautes performances à oxydes métalliques semi-conducteurs". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10192.
Testo completoFlexible electronics has experienced major advances in these last years. Indeed, the boom of flat panel displays (LCDs, AMOLED.) market is undergoing an exponential increase. One of the alternative solutions to amorphous silicon (a-Si) commonly used nowadays in these products is the development of metal oxide semiconductors. These materials are experiencing a huge consideration in both academic and industrial research, as well as in development labs due to their multiple performances. Besides their high electrical properties, with typical charge carrier mobilities in the order of 10 cm2V-1s-1. They can also be processed giving crystalline or amorphous structures. In this work, we have chosen to develop a complete chemical process based on the sol-gel technique to elaborate ternary metal oxide semiconductors, refered as In-(X)-Zn-O (IXZO) using different metal X as dopants. This innovative process for metal oxide semiconductors has allowed us to determine the best chemical composition, leading to a high stability and excellent electrical performances. Then, after having optimized the technological barriers (composition, doping, concentration, interfaces ...), we have characterized the nanostructure of these materials and evidence a phase segregation of the elementary oxides inside the material. We have also obtained a better understanding of charge transport properties in these semiconductors and assessed a percolation-based conduction model valid over a wide range of metal dopants. Finally, we have developed and optimized a combined thermal and UV flash lamp annealing process and demonstrated the feasibility of the integration of metal oxides on flexible substrates
OULD, EL MOCTAR CHEIKH. "Elaboration et etude de films de semi-conducteurs ternaires chalcopyrites a large bande interdite cualx 2(x = se, te), en perspective d'application photovoltaique comme couche tampon". Nantes, 1999. http://www.theses.fr/1999NANT2098.
Testo completoVermaut, Philippe. "Structure de couches de composes semi-conducteurs iii-v a large bande interdite, nitrure de gallium ou d'aluminium, epitaxiees sur carbure de silicum, par microscopie electronique en transmission". Caen, 1997. http://www.theses.fr/1997CAEN2019.
Testo completoGonnet, Jean-Marc. "Contrôle en ligne du moulage par injection des thermoplastiques semi-cristallins par spectroscopie diélectrique". Saint-Etienne, 2000. http://www.theses.fr/2000STET4003.
Testo completoMassaro, Loredana Maria. "Multimodal one-dimensional photonic crystal cavities". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP035.
Testo completoIntegrated photonics research focuses its efforts in developing miniaturised and efficient devices for applications in quantum information, metrology and medicine. In this context, photonic crystal cavities occupy a leading position in the integration of photonic structures owning small footprint and tailorable spectral properties. Special attention in recent years is given to photonic crystal cavities consisting of III-V semiconductor materials, as their nonlinear properties are an asset for further development in complex circuitry of coherent states of light through nonlinear interactions. In this thesis, we present the design, fabrication and experimental characterisation of high-Q one-dimensional photonic crystal cavities integrated on silicon on insulator. First, we detail the design of our cavities which is based on the gentle confinement of the field. We show that our design technique allows the devising of multimodal as well as single-mode photonic crystal cavities working at telecom window. The introduced design technique is versatile and easily tailorable to devise cavities of different materials, as InGaP, Si, or InP. Then, we detail the fabrication of III-V photonic structures heterogeneously integrated on silicon on insulator. From the adhesive bonding of the two levels to the final integrated device, fabrication process flow is reported and main challenges encountered commented. Fabrication of silicon-based cavities is also reported. Experimental characterisation of the cavities is conducted by measuring the transmission of the samples. We present how to tailor the spectral properties of the cavities through nanometric variation of their geometrical parameters, and comment on some peculiarities of multimodal coupling
Carbó, Meseguer Alexis. "Semiconductor optical amplifiers for ultra-wideband optical systems". Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2018. http://www.theses.fr/2018TELE0010.
Testo completoOver the last few decades the world has undergone a major revolution that has deeply affected the way we use communication networks. New services and applications have appeared demanding a constant increase of the channel capacity. In this period, optical systems have been upgraded at pair with advanced signal processing techniques which have permitted the increase of the spectral efficiency approaching the system capacity to the fundamental limit. It is because is becoming extremely challenging to keep growing the system capacity by this means. In this work, an orthogonal direction is studied to further increase the fibre capacity: extending the optical bandwidth. With this purpose, the use of semiconductor optical amplifiers (SOA) is investigated to be implemented in future ultra-wideband (UWB) systems. The use of SOA amplification changes completely the paradigm in the design of an optical system since all the impairments added by the SOA must be considered. In this work, we assess the reservoir model, a simple yet powerful model, to analyze numerically the nonlinear regime of the SOA for WDM systems. We also show for the first that the linewidth enhancement factor of an SOA can be estimated with a coherent receiver. Finally, it is also studied how the correlation between channels degrades significantly the performance of the SOA and the inclusion of a decorrelation fibre is investigated. The conception of a UWB system is then studied. We characterize a novel ultra-wideband SOA developed by the French project CALIPSO which presents high gain in a 100-nm optical bandwidth with high output saturation power and 6-8 dB of noise figure. We analyze its nonlinear regime for WDM systems and we show for QPSK and 16 QAM modulation formats that the input saturation power can be overtaken by serveral dBs without important nonlinear penalty. On the other hand, a novel technique is studied to compensate fibre nonlinearities in UWB systems: the multicarrier multiplexing, which tries to exploit the concept of symbol rate optimization. Finally, we assess the capabilities of this novel UWB SOA for data-centre interconnection applications with two experiments transmitting up to 113 Tbps data troughput in a 100-nm continuous bandwidth link over 100 km of fibre and then testings is stability with real-time line cards between two points of presence (POP)of Facebook deployed in the Paris area
Moreau, Eléonore. "ELABORATION DE GRAPHENE PAR EPITAXIE PAR JETS MOLECULAIRES ET CARACTERISATION". Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2011. http://tel.archives-ouvertes.fr/tel-00665851.
Testo completoViant, Jean-Nicolas. "Étude et conception de systèmes miniaturisés " intelligents " pour l'amortissement non-linéaire de vibration". Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00840864.
Testo completoCarbó, Meseguer Alexis. "Semiconductor optical amplifiers for ultra-wideband optical systems". Thesis, Evry, Institut national des télécommunications, 2018. http://www.theses.fr/2018TELE0010/document.
Testo completoOver the last few decades the world has undergone a major revolution that has deeply affected the way we use communication networks. New services and applications have appeared demanding a constant increase of the channel capacity. In this period, optical systems have been upgraded at pair with advanced signal processing techniques which have permitted the increase of the spectral efficiency approaching the system capacity to the fundamental limit. It is because is becoming extremely challenging to keep growing the system capacity by this means. In this work, an orthogonal direction is studied to further increase the fibre capacity: extending the optical bandwidth. With this purpose, the use of semiconductor optical amplifiers (SOA) is investigated to be implemented in future ultra-wideband (UWB) systems. The use of SOA amplification changes completely the paradigm in the design of an optical system since all the impairments added by the SOA must be considered. In this work, we assess the reservoir model, a simple yet powerful model, to analyze numerically the nonlinear regime of the SOA for WDM systems. We also show for the first that the linewidth enhancement factor of an SOA can be estimated with a coherent receiver. Finally, it is also studied how the correlation between channels degrades significantly the performance of the SOA and the inclusion of a decorrelation fibre is investigated. The conception of a UWB system is then studied. We characterize a novel ultra-wideband SOA developed by the French project CALIPSO which presents high gain in a 100-nm optical bandwidth with high output saturation power and 6-8 dB of noise figure. We analyze its nonlinear regime for WDM systems and we show for QPSK and 16 QAM modulation formats that the input saturation power can be overtaken by serveral dBs without important nonlinear penalty. On the other hand, a novel technique is studied to compensate fibre nonlinearities in UWB systems: the multicarrier multiplexing, which tries to exploit the concept of symbol rate optimization. Finally, we assess the capabilities of this novel UWB SOA for data-centre interconnection applications with two experiments transmitting up to 113 Tbps data troughput in a 100-nm continuous bandwidth link over 100 km of fibre and then testings is stability with real-time line cards between two points of presence (POP)of Facebook deployed in the Paris area
Lancry, Ophélie. "Étude par microspectrométrie Raman de matériaux et de composants microélectroniques à base de semi-conducteurs III-V grand gap". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10128/document.
Testo completoGaN based semi-conductors present numerous advantages linked essentially to their large band gap as compared to traditional Si systems. In addition, it is possible to form hetero-junction III-V HEMTs (High electron Mobility Transistor) like AlGaN/GaN which makes it possible to obtain both a large density of carriers confined at the heterojunction and a high electronic mobility. At the moment these systems are the most promising for high-power hyperfrequency applications. However heating occurs during operation which results in abnormal impacts on the performance of the microelectronic components. Micro-Raman characterization of these components makes it possible to understand the influence of the behaviour of the semi-conductor materials on the performance of the HEMTs in hyperfrequency mode. Micro-Raman spectroscopy being non-destructive and possessing a submicronic spatial resolution is well adapted to such studies. The use of various UV and visible excitation wavelengths (266 and 632.8 nm) makes it possible to probe the heterostructures at different penetration depths. We present results of micro Raman studies for analysis of the heterostructure composition, the stresses between layers, the thermal boundary resistance, the crystalline quality of each layer and the doping and thermal behaviour of each layer. In addition, recent time-resolved UV micro-Raman studies have made it possible to analyse the transient thermal behaviour of AlGaN/GaN HEMTs under voltage and in the active area of the component
Viant, Jean-Nicolas. "Étude et conception de systèmes miniaturisés « intelligents » pour l’amortissement non-linéaire de vibration". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10132/document.
Testo completoMechanical vibration damping has many applications in industry (machine tools), civil engineering (bridge construction), or aeronautics (stress during maneuvers). Current research tends mainly to use piezoelectric materials based methods. A promising technique from the LGEF of INSA Lyon is the vibration damping of mechanical structure by so-called SSDI method (for Synchronized Switch Damping on an Inductor). This semi-active damping technique uses a non-linear process to invert the voltage across a piezoelectric element. The element is used as sensor and actuator at a time. The aim of this work is to achieve an integration of the electronic process with the SSDI voltage inversion in a microelectronic technology. It has ultimately to embed the electronic controller on the piezoelectric patch. The analysis of published damping techniques can situate this work and identify key points of the SSDI technique. In the second chapter, several models are developed to compare and decide of the best architectural design choice. The third chapter presents an ASIC design in a technology with high voltage option. The ASIC consists of a high-voltage piezoelectric signal processing part and a low-voltage control part. The first function performs piezoelectric voltage reversing by mean of a passive RLC energy conversion circuit. The second function focuses on the extremum voltage detection circuit in order to optimize damping efficiency. A self-tuning voltage divider with over-voltage protection and a peak voltage detector can perform this operation. These functions are characterized by simulations and measurements. The ASIC operation is then tested with mechanical structures, and damping performances are described and interpreted in Chapter 4. The multimodal behavior and the mechanical signals high-dynamic are new contribution as regard in the bibliography
Goualard, Olivier. "Utilisation de semi-conducteurs GaN basse tension pour l'intégration des convertisseurs d'énergie électrique dans le domaine aéronautique". Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/20325/1/GOUALARD_Olivier.pdf.
Testo completoSandana, Eric Vinod. "SYNTHÈSE ET MAÎTRISE DE LA CROISSANCE DE NANOCRISTAUX : APPLICATIONS AUX COMPOSANTS A BASE DE SEMI-CONDUCTEURS A GRANDE BANDE INTERDITE". Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00640652.
Testo completoNikaj, Erisela. "Mobilité moléculaire aux interfaces de systèmes nanostructurés". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10255.
Testo completoThe aim of this work was to study the molecular dynamics in several polymeric nanostructured and confined systems. Thus, by means of Dielectric Spectroscopy, the molecular mobility of cellulose acetate (rigid chain) grafted poly(methyl (diethylène glycol) methacrylate) (very mobile chains) copolymers were studied. In this case, an increase of the mobility of the main chain and a reduction of the mobility of the grafted moieties have been observed. The confinement effects induced by the presence of the crystalline lamellae on the mobility of the chains belonging to the amorphous region, was also studied as a function of the morphology, in the case of the amorphous films of Poly(ethylene naphtalene - 2,6 - dicarboxylate) (PEN) which were crystallized at different crystallization temperatures during different crystallization times. A strong influence of the crystallization temperature on the molecular dynamics of PEN has been evidenced: in the case of the samples crystallized at high temperatures, the mobility of the chains was higher than in the case of the samples crystallized at low temperatures. Finally, the confinement effects induced by the Montmorillonite (MMT) platelets on the Polyamide 6 (PA6) matrix were studied in the PA6/MMT nanocomposites. No significant influence of the filler on the molecular mobility of the PA6 chains was observed. Nevertheless, as expected, the two interfacial relaxations were very sensitive to the filler content
Benchikhi, Mohamed. "Élaboration par chimie douce et caractérisations de semi-conducteurs nanométriques à base de sulfures (de type CuInS2) et d'oxydes (de type CuMoO4)". Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1866/.
Testo completoThis manuscript decals with the elaboration by soft chemistry and the structural, morphological and physical characterization of semi-conductors based on: - Metallic sulfides CuInS2, CuIn(1-x)GaxS2, Cu2SnZnS4. - Metallic oxides CuMoO4, CuMo(1-x)WxO4. These materials exhibit potential applications on the field of photovoltaic conversion. The first part is concerned with the elaboration of nanoparticles of CuInS2 and Cu2SnZnS4. Tow synthesis methods are considered for the elaboration of these pure or doped sulfides, in the shape of nanometrical powders. The first method involves the reaction of metallic chlorides with a molten potassium thiocyanate medium (400°C). It is used for the first time for the synthesis of CuInS2 and Cu2SnZnS4. The second one is the polyol process. The precipitation occurs in ethylene glycol medium at 200°C. It is followed by a thermal treatment in molten potassium thiocyanate. The second part is devoted to the study of molybdates CuMo(1-x)WxO4 (With 0 = x= 0. 12). Four synthesis routes were used for the elaboration of these molybdates: solid state reactions, the Glycine-nitrate process (G. N. P), the acrylate way (steric trapping) and the citrate route. The syntheses were optimized and the powders obtained characterized by XRD and thermal analysis. The granulometry and the morphology of powders are dependent upon several parameters: The synthesis method, the source of copper, the pH, the citric acid/Cu ratio (Cit/Cu), the calcinations temperature and the concentration in tungsten. The gap of powders, evaluated by UV-visible absorption spectroscopy varies between 2. 02 eV for the molybdate a-CuMoO4 and 1. 67 eV of the molybdate γ-CuMo0,88W0,12O4. The last part of this work is dedicated to the sintering processes were investigated: conventional sintering and spark plasma sintering (SPS). The relative densities obtained for the non doped molybdate are respectively 95 and 99%. The SPS sintered ceramic exhibits a grain size (0,5 micrometre) significantly lowers than that (2 micrometre) of the conventionally sintered ore. A preliminary study of the sintering of CuMo(1-x)WxO4 (With 0 = x= 0. 12) has shown that the structure and the microstructure of the ceramics obtained is dependent upon the sintering method and the tungsten content
Le, Trung Kien. "Physical layer design for ultra-reliable low-latency communications in 5G". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS198.
Testo completoThe advent of new use cases and new applications such as augmented/virtual reality, industrial automation, autonomous vehicles, etc. in 5G has made the Third Generation Partnership Project (3GPP) specify Ultra-reliable low-latency communications (URLLC) as one of the service categories. To support URLLC with the strict requirements of reliability and latency, 3GPP Release 15 and Release 16 have specified the URLLC features in licensed spectrum. The ongoing 3GPP Release 17 extends the URLLC features to unlicensed spectrum to target the new use cases in the industrial scenario. In the first part of the thesis from Chapter 2 to Chapter 4, we focus on the URLLC in licensed spectrum. The first study deals with the problem of ensuring the configured number of uplink (UL) configured-grant (CG) repetitions of a transport block. Secondly, we study the collisions of an eMBB UL transmission of a user equipment (UE) and an URLLC UL transmission of another UE on the CG resources. Thirdly, the focus of this study is the downlink (DL) transmission where the feedback of the DL semi-persistent scheduling transmission is dropped due to the conflict of the DL/UL symbols. In the second part from Chapter 5 to Chapter 8, we focus on URLLC operation in unlicensed spectrum. In unlicensed spectrum, a 5G device is required to access to a channel by using load based equipment (LBE) or frame based equipment (FBE). The uncertainty of obtaining channel access through LBE or FBE can impede the achievement of the URLLC latency requirements. Therefore, the study of impact of LBE and FBE on URLLC transmission and the enhancements of LBE and FBE are needed
Junior, Carlos Cesar Brochine. "Metodologia semi-analítica para predição de ruído de banda larga causado pela interação entre a esteira turbulenta do rotor com as aletas da estatora em motores turbofans". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-26102016-101909/.
Testo completoThe major noise source in aircraft is the engine. Since tonal noise control is well developed, the current effort concentrates on broadband noise reduction, which is less understood. The broadband noise is generated when a turbulent flow interacts with a surface as, for example, rotor blade tip flow, boundary layer and the rotor interaction. Although there are different sources of broadband noise it is known that the major broadband source in turbofan engine is the rotor turbulent wake interacting with the stator vanes. This study is focused in that source of noise and the goal is to develop a model capable of predicting the rotor/stator interaction noise as well as in duct noise propagation. Noise prediction can be carried out by analytical, numerical or empirical methods, each one with advantages and disadvantages. In the present work the semi-analytical method was used. Turbulence characteristics were estimated by a numerical method and the noise generation and duct propagation was estimated by an analytical method. The biggest advantage comparing with the numerical methods is that this method is less time consuming. A purely analytical method would require excessive geometric simplification. The ANCF, a rig developed by NASA was used as basis for the simulations, since its geometry and noise data are available. The results show that the correct trends are consistently captured. So it is concluded that it is possible to predict the broadband noise and its propagation in turbofans engines with a practical and low cost method.
Taki, Haidar. "On ultra-wideband over fiber transmission systems employing semiconductor optical amplifiers". Thesis, Brest, 2017. http://www.theses.fr/2017BRES0071/document.
Testo completoUltra WideBand (UWB) over fiber is a promising technology for meeting the demands of future wireless local-area networks (WLANs) and wireless personal-area networks (WPANs). Thanks to the enormous bandwidth and fiber characteristics, a high communication quality may be established at long reach. UWB wireless propagation must be achieved with special power and spectral constraints fixed by the regulatory bodies (e.g. US Federal Communication Commission). The novelty of our work originates from exploiting the benefits of a Semiconductor Optical Amplifier (SOA) so as to get a reach extension at limited cost and complexity. However, the inherent nonlinear effects and Amplified Spontaneous Emission (ASE) noise associated to such device may affect the system performance.Overcoming these impairments has been of central importance in this study. SOA nonlinearities have been mitigated by applying analog pre-distortion in electrical domain. Phaser-based processing was also proposed to simultaneously reduce ASE influence and linearize SOA characteristics, thanks to up/down chirping performed on the transmitter/receiver sides. With Impulse Radio UWB transmission, due to the time properties of modulation patterns, discrete lines arise in the corresponding spectrum, which may violate FCC limit or reduce the power efficiency. A new shape randomization technique has been investigated, which proved to be effective in suppressing these spectral spikes. The three approaches have shown a great potential with On Off Keying and Pulse Position Modulation formats at long optical reach.The performance of Differential Chaos Shift Keying was finally examined in the over fiber system, a lower error probability was experimentally achieved in comparison with other non-coherent modulations