This dissertation argues on the necessity for an efficient and credible recovery and resolution framework for central clearing counterparties (CCPs).Following the 2008 subprime crisis and the failure of Lehman Brothers, several reforms have been undertaken in order to reinforce the strength of the financial system and, in particular, the over the counter (OTC) derivatives market. Two streams of reforms are of particular relevance in the present context: a) The development of resolution regimes for financial institutions, in particular for systemic “too big to fail” banks. The key objectives of these resolution regimes are to ensure the continuity of the critical functions performed by systemic institutions, the preservation of financial stability and the protection of taxpayers (i.e. avoiding public bailouts). This stream completed regulatory initiatives to reinforce the existing prudential framework acknowledging the natural limits of the latter and the observed forbearance by supervisory authorities in the aftermath of the financial crisis. The academic literature analysing the development and implementation of resolution regimes for banks essentially looked at issues such as the respect of the shareholders’ fundamental rights, the existence of appropriate safeguards for creditors and the execution of bail-in operations. b) The obligation to clear centrally OTC derivatives markets in order to prevent and control the possible contagion of risks across the financial system. The objectives of this stream of reform are to increase the transparency of the OTC derivatives markets and reduce the counterparty credit risk in the system by forcing transactions through professional risk managers, i.e. central clearing counterparties (CCPs). This however assumes that CCPs have the capability and the capacity to manage this centralisation of risks. Therefore, the literature showed interest in the risk management practices of CCPs, in particular margining methodologies, and agency problems created by the ownership structure and the loss allocation mechanisms of CCPs, in particular analysing the effects of a CCP’s skin-in-the-game (i.e. own contributions to the loss allocation mechanisms) on the incentives of shareholders and clearing members. Although recent history has been rather merciful in terms of CCPs' failures, the inherent cross-border and international nature of their activities, their level of interconnectedness with other financial institutions and their growing importance following the G20 commitments on OTC derivatives make them critical nodes of the financial system. It is therefore important to consider carefully the recovery and resolution of CCPs that actually stands at the crossroad of the two streams of regulatory reforms mentioned above and completes them. Similarly, this dissertation intends to build the bridge between the literature on CCPs and the literature on banks’ recovery and resolution. It aims at providing a better understanding of the resolution framework developed for CCPs, associated policy choices and possible issues with a specific insight on the situation in Europe. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

<p>Credit derivatives are very popular on financial markets in recent days.</p><p>The most liquid credit derivative is a credit default swap (CDS). In</p><p>this research we investigate methods for modeling and monitoring of the</p><p>price process of CDS. We study Hull and White model to calculate CDS</p><p>spread and have data for our analysis. We consider different methods for</p><p>monitoring of the price process of CDS. In particular we study CUSUM</p><p>method. And we calculate more commonly used perfomance measures</p><p>for this method.</p>

Ce travail de thèse présente les caractéristiques optiques et électriques de dopants dans des couches de CdHgTe, CdZnTe et CdS. Ces 3 matériaux II-VI ont pour point commun d'être utilisés dans des dispositifs de détection, que ce soit la détection de lumière infrarouge pour les couches de CdHgTe et CdZnTe ou la détection visible comme c'est le cas pour le CdS. La caractérisation optique de ces couches de matériaux II-VI a été réalisée par la technique de photoluminescence et corrélée à des mesures électriques effectuées par effet Hall en température. Dans un premier temps, une étude du dopage intrinsèque par les lacunes de mercure et du dopage extrinsèque par incorporation d'arsenic de l'alliage CdHgTe, couche active des détecteurs IR a été réalisée. Pour cela, des mesures optiques par photoluminescence (sur un banc mis en place au laboratoire pendant la 1ere année de thèse permettant de travailler depuis les basses températures jusqu'à l'ambiante entre 1µm et 12 µm dans l'IR) sur des couches de CdHgTe réalisées par épitaxie en phase liquide (EPL) de différentes compositions en Cd ont été effectuées. La corrélation de ces mesures optiques avec des mesures électriques par effet Hall en température a permis d'identifier les énergies d'activation des 2 niveaux de la lacune de mercure ainsi que de démontrer le phénomène de U-négativité de la lacune de mercure dans le CdHgTe. De plus, la comparaison de spectres de PL d'échantillons dopés arsenic pendant la croissance par épitaxie par jets moléculaires (EJM) avec des mesures disponibles réalisées par absorption de rayons X (EXAFS) a permis d'observer des transitions optiques associées aux différents complexes arsenic formés avant et après le recuit d'activation. Par ailleurs, un travail de modélisation du phénomène de désordre d'alliage dans le CdHgTe a été réalisé. Plus précisément, un modèle basé sur une statistique gaussienne associée aux fluctuations d'alliage autour d'un gap moyen et une statistique de Boltzman a été développé pour ajuster dans un premier temps des spectres d'absorption puis pour ajuster les spectres de photoluminescence. Ce modèle nous a permis d'ajuster étroitement les spectres de photoluminescence et d'absorption, tout en prenant en compte intrinsèquement le désordre d'alliage du matériau. Nous avons ainsi constaté que l'ajustement des spectres par des fonctions gaussiennes comme il est réalisé communément dans la littérature permet de trouver les bons écarts entre les pics d'émission et donc les bonnes énergies d'ionisation.. Dans un deuxième temps, toujours dans le cas de la détection infrarouge, le travail a porté sur l'étude du substrat CdZnTe utilisé pour l'épitaxie du CdHgTe. Des comparaisons des spectres de PL avec les paramètres de croissance ont été effectuées. Plus particulièrement, une étude sur une zone spécifique de certains échantillons présentant une absorption du rayonnement IR a été réalisée afin d'en comprendre l'origine. Enfin, nous nous sommes intéressés à la couche de CdS, matériau II-VI dopé intrinsèquement (type n) utilisé comme fenêtre transparente et formant la jonction p-n avec le CdTe dans les cellules solaires, détecteurs de lumière visible. Dans cette partie, nous avons chercher à étudier l'influence des différentes méthodes de dépôts, sublimation ou bain chimique de la couche de CdS sur un substrat de verre, en comparant les spectres d'émission de photoluminescence obtenus ainsi que les types de traitements thermiques effectués après dépôts. Ces mesures ont été corrélées avec le rendement des cellules solaires finales.

Thin film solar cells, if film thickness is thinner than the optical absorption length, typically give lower cell performance. For the thinner structure, electric current loss due to light penetration can offset the electric current gain obtained from higher built-in electric field. Light trapping schemes can increase the effective optical absorption length and thus enhance the electric current for thinner solar cells. Here a new light trapping scheme based on light trapping transparent conducting oxide layer (LT-TCO) is proposed to enhance the performance of thin film solar cells. Three different configurations of integrating the LT-TCO layer in solar cells are proposed and evaluated. This research aims to develop the LT-TCO layer with surface texture and good conductivity by pulsed laser deposition (PLD) technique at low temperature. The LT-TCO layer is fabricated by PLD deposition of Al-doped ZnO to achieve multilayer films by tuning of oxygen pressure. The light trapping effect is examined by optical transmittance measurement and the surface texture is characterized by transmission electron microscopy (TEM) technique. The conductivity of LT-TCO layer is measured by resistivity measurement. Thin film CdTe/CdS solar cells are fabricated by PLD technique to develop baseline solar cells for integration of LT-TCO layer. The as-deposited thin film solar cells show relatively low performance and are further processed with various post-deposition treatments to seek efficiency enhancement. The effects of different processes on cell performance are examined by electrical, optical, and microstructure studies. Air annealing of CdS layer and CdCl2 treatment of CdTe layer combined are found to yield the best cell performance. The fabrication issues that limit the cell performance are discussed and future optimizations in fabrication processes are suggested.

In this study , we investigate the relationship between growth condition and thin film quality of cadmium sulfide (CdS) thin films grown by chemical bath deposition (CBD) method. Thin film structures are analyzed by X-ray diffraction , morphology and grain size are obtained by scanning electronic microscopy , and film thickness measured by reflectance spectroscopy . In medium pH value ( pH=10.5) , 20 min deposition can achieve 450 nm film thickness . At lower pH (pH=8.5), low hydrolysis rate of thiourea limits the concentration of sulfur anion , film thickness is only 49 nm after one hour deposition at 70 ¢J , and the obtained thin film can not fully cover the substrate to have a pin-hole free film . At higher pH (pH=11), 40 min only deposites 100 nm film thickness. Strong binding between the cadmium ion and the complexing agent causes low free cadmium cation concentration in the solution, which limits the growing rate. By varying the growth pH condition, the difference in thickness is more than one order of magnitude. In contrast to the film thickness relationship, grain size distribution suffers less influence from the pH consition. Our results indicate no explicitly relation between the grain size and solution pH condition. 20 minutes depositions result cadmium sulfide grain sizes to be 70¡Ó10nm , and 40 minutes result grain size to be 75¡Ó15nm . The results indicate that film thickness increases mainly due to the increasing of grain number, rather than the increasing of grain size . By summarized the results, we propose that the deposition of cadmium sulfide film is initially formed homogeneous nucleation in the solution. The nuclea diffuse and adhere to the substrate. Intristic electric dipole momentum of the cadmium sulfide nano-particle provides an attractive force for the adhesion, and results preferred orientation. Meanwhile, the grain keeps growing up until the size saturated .

Coverage in a Wireless Sensor Network reflects how well a sensor network monitors an area. Many times it is impossible to provide full coverage. The key challenges are to prolong the lifetime and ensure connectivity to provide a stable network. In this thesis we first define p-percent coverage problem in which we require only p% of the whole area to be monitored. We propose two algorithms, Connected P-Percent Coverage Depth First Search (CpPCA-DFS) and Connected P-Percent Connected Dominating Set (CpPCA-CDS). Through simulations we then compare and analyze them for their efficiency and lifetime. Finally in conclusion we prove that CpPCA-CDS provides 5 to 20 percent better active node ratio at low density. At high node density it achieves better distribution of covered area however the lifetime is only 5 to10 percent shorter then CpPCA-DFS. Overall CpPCA-CDS provides up to 30 percent better distribution of covered area.

Photovoltaic devices are receiving growing interest in both industry and research institutions due to the great demand for clean and renewable energy. Among all types of solar cells, cadmium sulfide (CdS) – cadmium telluride (CdTe) and cadmium sulfide (CdS) - copper indium diselenide (CuInSe2 or CIS) heterojunctions based thin film solar cells are of great interest due to their high efficiency and low cost. Further improvement in power conversion efficiency over the traditional device structure can be achieved by tuning the optical and electric properties of the light absorption layer as well as the window layer, utilizing nano template-assisted patterning and fabrication. In this dissertation, simulation and calculation of photocurrent generation in nanowires (NW) based heterojunction structure indicated that an estimated 25% improvement in power conversion efficiency can be expected in nano CdS – CdTe solar cells. Two novel device configurations for CdTe solar cells were developed where the traditional thin film CdS window layer was replaced by nanowires of CdS, embedded in aluminum oxide matrix or free standing. Nanostructured devices of the two designs were fabricated and a power conversion efficiency value of 6.5% was achieved. Porous anodic aluminum oxide (AAO) was used as the template for device fabrication. A technology for removing the residual aluminum oxide barrier layer between indium tin oxide (ITO) substrate and AAO pores was developed. Causes and remedies for the non-uniform barrier layer were investigated, and barrier-free AAO on ITO substrate were obtained. Also, vertically aligned nanowire arrays of CIS of controllable diameter and length were produced by simultaneously electrodepositing Cu, In and Se from an acid bath into the AAO pores formed on top of an aluminum sheet. Ohmic contact to CIS was formed by depositing a 100 nm thick gold layer on top and thus a Schottky diode device of the Au/CIS nanowires/Al configuration was obtained. Material properties of all these nanowires were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), absorption measurement. Current-voltage (I-V), capacitance-voltage (C-V) and low-temperature measurements were performed for all types of devices and the results were analyzed to advance the understanding of electron transport in these nano-structured devices.

Indium tin oxide (ITO) and molybdenum are substrates of choice in the manufacture of the CdS-CIS photovoltaic cell, which is the base for the leading thin-film solar cell technology. Substantial advancement in this technology is expected if these devices can be made in nanoporous alumina (AAO) templates. The first step to this endeavor is to learn to form AAO templates on molybdenum and ITO substrates. This was accomplished, and the results are reported in this thesis. Starting substrates were glass, coated with either a thin molybdenum layer or a thin ITO layer. Aluminum was deposited on top of this conducting substrate. Oxalic acid was used as the electrolyte for anodization. In the case of molybdenum substrates, average pore diameter was 45 nm when an anodization voltage of 40 volts was used for approximately 46 minutes; current density was approximately 23 amps/sq. m. In the case of ITO substrates, pores of 45 nm diameter were obtained for approximately 20 minute anodization at 40 V; current density was 40 amps/sq. m; annealing of aluminum layer prior to anodization, at 550 oC (degrees Centigrade) for 90 minutes was needed to obtain good pores. A one micrometer thick CdS layer was electrodeposited inside the AAO pores on top of the ITO substrate. In preliminary experiments, CdS/Cu2S photovoltaic heterojunctions with an open circuit voltage of 242 mV were formed inside the nanopores.

This work aims to study the variation in electrical and optical properties of nanoscale Schottky diodes by varying their dimensions in the nanoscale. Experimental conditions for fabricating porous alumina with varying pore diameters and inter-pore distances were first optimized by anodizing Aluminum tape with variable currents. Cadmium Sulfide nanowires were then synthesized inside the membranes by dc electrodeposition. Finally a high work function metal was deposited on top as a contact for the metal-semiconductor Schottky diode junction. As a comparative study, Schottky diodes fabricated using the same metals and Cadmium Sulfide thin films deposited on conducting glass substrates using electro-deposition and annealed in different ambient were also studied. Device characterizations were carried out by field-emission scanning electron microscopy (FESEM), current voltage (I-V) measurements, ultraviolet-visual (UV-Vis) absorption spectroscopy and X-Ray diffraction.

CdS thin films were deposited by thermal evaporation method onto glass substrates without any doping. As a result of the structural and electrical investigation it was found that CdS thin films were of the polycrystalline structure and n-type / and of the transmission analysis optical band gap was found to be around 2.4 eV. Temperature dependent conductivity measurements were carried out in the range of 180 K &ndash / 400 K. The dominant conduction mechanism is identified as tunnelling between 180 K &ndash / 230 K and thermionic emission between 270 K and 400 K. To produce Schottky devices, CdS thin films were deposited onto the tin-oxide and indium-tin-oxide coated glasses, by the same method. Gold, platinum, carbon and gold paste were used as metal front contact in these devices. The area of these contacts were about...... Temperature dependent current-voltage measurements between 200 K and 350 K, room temperature current-voltage measurements, capacitance-voltage measurement in the frequency range 1 kHz &ndash / 1 MHz and photoresponse measurements were carried out for the characterization of these diodes. Ideality factor of the produced Schottky devices were found to be at least 1.5, at room temperature. Dominant current transport mechanism in the diodes with gold contacts was determined to be tunnelling from the temperature dependent current voltage analysis. Donor concentration was calculated to be about ........ from the voltage dependent capacitance measurement.