L'optique quantique réalisée à l'échelle du nanometer est un défit crucial, surtout pour la caractérisation d'émetteur de photon unique. Ces émetteurs sont des défauts ponctuels dans des matériaux (quelques angströms) ou des structures confinées de quelques nanomètres. Une façon d'atteindre cette échelle est d'utiliser la cathodoluminescence (CL) dans un microscope électronique à transmission à balayage (CL-STEM) [1]. Cependant, lorsque l'on cherche à étudier les propriétés statistique d'émission de la lumière sortant d'une expérience de CL, ce qui est nécessaire pour étudier par exemple la nature quantique d'émetteur de photon unique (SPE), une expérience dédiée s'ajoutant à l'expérience de CL-STEM doit être réalisée. Quelques mois avant mon arrivé dans le groupe STEM du LPS, une expérience d'interférence des intensités (HBT) qui mesure la fonction d'autocorrélation g(2)(τ) du signal de CL a été construit [2]. Il est bien connu que la signature univoque d'un SPE en photoluminescence (PL) est l'antibunching, c'est à dire que le g(2)(τ) est toujours inférieur à un. Il a été récemment démontré que lorsque seulement un SPE est excité la CL-STEM est similaire à la PL sur un célèbre SPE, le centre NV dans le diamant. Dans cette thèse nous montrerons comment la CL-STEM a permis de caractériser un nouveau défaut ponctuel dans le h-BN, montrant la pertinence de l'expérience HBT dans un CL-STEM pour découvrir et caractériser de nouveaux SPE. Cependant, en étudiant l'excitation de multiple SPE en CL, on a découvert un nouveau phénomène d'émission, caractérisé par un grand effet de regroupement (bunching) dans la fonction g(2) (g(2)(0) > 35), en complète contradiction avec les mesures de PL et ce que l'on pourrait attendre (g(2)(0)< 1). Dans mon manuscrit de thèse, cet effet surprenant a été expérimentalement étudié, expliqué théoriquement et appliqué à la mesure de temps de vie à l'échelle du nanomètre. Parce que l'optique quantique est souvent liée à la plasmonique quantique, je présenterai pour conclure une proposition théorique en collaboration avec Javier Garcia de Abajo pour étudier la plasmonique quantique dans un microscope électronique à transmission à balayage. / Quantum optics performed at the nanometer scale is an important challenge, especially for quantum emitters characterization. They can be point defects in material (few ang- ströms) or confined structures of a few nanometers. A way to reach this scale is by using cathodoluminescence (CL) performed in a scanning transmission electron microscope (CL- STEM), which has only recently been done [1]. However, when aiming at studying the statistical properties of the light coming out of a CL experiment, which is necessary to e. g. study the quantum nature of Single Photon Emitters (SPE) emission, dedicated expe- riments on top of regular CL ones have to be designed. Few months before my arrival in the STEM-group of the LPS, an intensity interferometry experiment (HBT) that measures the autocorrelation function g(2) of the CL signal intensity was built [2]. It is well known that the clear signature of SPE as measured in photoluminescence (PL) is antibunching in the g(2)(τ), namely that the autocorrelation function is always less than one. It was re- cently demonstrated on a famous SPE, the Nitrogen vacancy (NV) defect in diamond, that CL-STEM is similar to PL when only one SPE is involved. In this thesis we will see how CL-STEM allowed to characterize a new point defect in h-BN, showing the relevance of HBT experiments in a CL-STEM for discovering and characterizing new SPE. However, by studying the excitation of multiple SPE in CL, we discovered a new emission phenomenon, characterized by a huge bunching effect of the g(2)(τ) function (g(2)(0) > 35), in complete contradiction to PL measurements and expectations (g(2)(0)<1). In my thesis manuscript, this surprising effect will be experimentally investigated, theoretically explained and applied to lifetime measurement at the nanometer scale. Because quantum optics is often linked to quantum plasmonics, I will present, to conclude, a theoretical proposal, in collaboration with J. Garcia de Abajo, about quantum plasmonics measurement in a STEM.

The Big Clifty is a Chesterian-age Mississippian sandstone member of the Golconda Formation that extends from south-central Kentucky into adjacent Illinois and Indiana. Asphaltic deposits and conventional petroleum plays are distributed along the Pennyrile Fault System and Plateau in the southeastern portion of the Illinois basin. In south-central Kentucky anomalous oil-saturation geometries are observed in cored sections of the Big Clifty from wells in Warren and Butler counties along the margin of the Pennyrile Plateau. Petrographic study of the cores has revealed several diagenetic processes that have contributed to, or are directly responsible for, the anomalous oil saturation geometries and resultant reservoir partitioning. This study utilizes standard transmitted and reflected light microscopy, UVepifluorescence, optical cold-cathode cathodoluminescence microscopy, scanning electron microscopy, and alizarin red S and potassium ferricyanide staining in petrographic examination. Raman microscopy, energy-dispersive X-ray spectroscopy, transmitted electron microscopy, and X-ray diffraction assisted in identification and compositional analysis of minerals. Quantification of framework grains and cement compositions, porosity, and grain-size distributions was also conducted. This study’s data classified the Big Clifty as a fine to very-fine grained, quartz arenite with predominantly silicious and phyllosilicate cements and a mean of porosity of 7%. Oil-saturation geometries concordant to rock fabric are due to compaction, weathering of labile grains, and precipitation of authigenic cements (mainly quartz, kaolinite, and pyrite). A paragenetic sequence, established from textural evidence, places quartz, kaolinite, and pyrite phases early in paragenesis with labile grain dissolution, compaction, and precipitation of ferroan carbonate cement, with development of vugular porosity occuring later during burial. These phases and processes enhanced preexisting porosity and permeability heterogeneities within the rock. Nodular pyrite, oil emplacement, and precipitation of poikilotopic calcite are the latest diagenetic events. Nodular pyrite and poikilotopic calcite are responsible for oil-saturation geometries distinctly discordant with rock fabric. Poikilotopic calcite forms interstratal seals, occluding porosity, replacing framework grains and cements, and overprinting primary rock fabric. This study’s preliminary research into the poikiloptopic calcite suggests its occurrence is possibly associated with the cored wells’ shallow depths less than 500 feet (150 meters), and proximity to near-vertical faults and waters from drainage systems of karstified carbonate aquifers updip.

GaN et ses alliages ternaires et quaternaires du système Ga(B,In,Al) sont devenus au cours des dernières années des semiconducteurs phare de l'optoélectronique. Plus spécifiquement l'alliage InGaN qui présente une énergie de bande interdite (0, 77eV, pour l'InN à 3, 4eV, pour le GaN) permettant l'absorption quasi totale du spectre visible se positionne comme un excellent candidat pour la réalisation de cellules solaire multi-jonctions à très haut rendement. La croissance de couches épitaxiales d'InGaN avec une forte teneur en indium et une bonne qualité structurale et morphologique reste néanmoins un challenge. Notre groupe a été parmi les premiers à relever ce challenge en proposant une technique de croissance originale consistant à insérer périodiquement de fines couches de GaN dans la couche épaisse d'InGaN. Ce travail s'inscrit dans ce contexte et porte sur les caractérisations morphologiques, structurales et optiques des différentes structures élaborées et qui ont permit l'optimisation du procédé de croissance et l'obtention de couches d'InGaN avec une teneur en indium de 15%, une épaisseur de 120nm et des qualités structurales et optiques de premier ordre. La partie centrale du travail a consisté en la mise en oeuvre et l'utilisation de la technique de cathodoluminescence pour l'étude des matériaux InGaN élaborés au laboratoire par MOVPE. Les principales avancées de ce travail, outre la contribution au succès de l'obtention de couches d'InGaN de grande qualité, concernent la confirmation du mode de croissance des couches d'InGaN (transition 2D-3D, type et rôle des inclusions de surface), la détermination de l'épaisseur critique des couches en fonction du taux d'indium, et la modélisation du phénomène de cathodoluminescence par méthode Monte-Carlo / GaN and its ternary and quaternary alloys Ga(B, In, Al)N have become in recent years one of the most important semiconductor materials for applications in optoelectronics. More specifically, the InGaN alloy, that has a band gap energy (0.77eV for InN, 3.4eV for GaN) allowing almost full absorption of the visible spectrum can be an excellent candidate for the realization of highly efficient multi-junctions solar cells. However, the growth of InGaN epitaxial layers with high indium content and good structural and morphological quality remains a challenge. Our group was among the first to meet this challenge by proposing an original growth technique consisting in the periodical insertion of thin GaN layers in the thick InGaN layer. The present work falls in this context and focuses on the morphological, structural and optical characterization of different InGaN structures that have been developed, allowing the optimization of the growth process and the obtention of InGaN layers with an indium content of 15%, a thickness of 120nm and a high structural and optical quality. The main aspect of the present work consist in the implementation and use of the cathodoluminescence technique to study the InGaN materials grown by our group using MOVPE. The main achievements of this work, in addition to the contribution to the success of getting high quality InGaN layers, relate to the confirmation of the growth mode of InGaN layers (2D - 3D transition, type and role of surface inclusions), the determination of the critical layer thickness according to the indium content, and the modeling of the cathodoluminescence phenomenon using Monte Carlo method

This thesis presents the results of a combined cathodoluminescence (CL) and electron paramagnetic resonance (EPR) spectroscopic study of quartz from the uranium-mineralized Athabasca Basin. CL imaging not only distinguishes detrital quartz grains from their secondary overgrowths but also is able to differentiate two generations of overgrowths in the Athabasca sandstones. Moreover, the Athabasca quartz samples are characterized by three types of bright CL: 1) haloes around U- and Th-bearing mineral inclusions, 2) patches associated with U-bearing minerals in matrices or pores and 3) continuous rims in samples with or without any visible U-bearing minerals. These three types of bright CL are all of constant widths of ~35-45 Ým, indicative of bombardments of alpha particles emitted from the 238U, 235U and 232Th decay series. CL spectral analyses show that the radiation damaged areas, relative to their undamaged hosts, are characterized by intense but broad emission bands at ~350 nm and 620-650 nm. <p>Detailed EPR measurements of the Athabasca quartz samples revealed six paramagnetic defects: one oxygen vacancy center (E1'), three silicon vacancy hole centers (O23¡V/H+(I), O23¡V/H+(II) and O23¡V/M+) and two O2¡V peroxy centers. Moreover, dissolution experiments using concentrated HF showed that that the silicon vacancy hole centers and the peroxy centers are concentrated in the radiation-damaged rims/fractures, whereas the oxygen vacancy center (E1') is evenly distributed in quartz grains. CL and EPR data of quartz samples after isochronal annealing experiments suggest that the silicon vacancy hole centers and the peroxy centers are most likely responsible for the characteristic ultraviolet CL and the red CL, respectively. <p>CL haloes in detrital quartz grains are ubiquitous in the Athabasca sandstones. CL patches are also widespread but are best developed in altered sandstones close to the unconformity or faults/fractures. Continuous CL rims, however, are more restricted in occurrences and are best developed at the high-grade Cigar Lake and McArthur River deposits, where they are restricted to lithological boundaries and faults and are pervasively developed in mineralized samples and associated alteration haloes close to the unconformity. At the Key Lake deposit, continuous rims occur only in mineralized samples close to the unconformity. Continuous CL rims are absent in basement rocks below mineralization, including those at the Cigar Lake and McArthur River deposits. The occurrence of radiation damages in Athabasca quartz have also been confirmed by detailed EPR measurements, which are significantly more sensitive than CL imaging. <p>Continuous CL rims on Athabasca quartz grains most likely record bombardments of alpha particles emitted from U-bearing mineralization fluids. Therefore, their associations with the unconformity, lithological boundaries and faults provide direct evidence for those structures being the pathways for mineralization fluids. The exclusive occurrence of continuous CL rims on detrital quartz grains and the abundance of U-bearing minerals in both generations of overgrowths suggest that U mineralization must have commenced during early diagenesis and continued during the formation of overgrowths. The absence of significant radiation damages in altered basement rocks supports the hypothesis that the basement was not a major source for uranium mineralization in the Athabasca basin. The common occurrence of CL haloes in euhedral quartz grains and CL patches associated with U-bearing minerals in faults, fractures and voids provide further (visual) evidence for late remobilization of uranium.

This thesis presents the results of a combined cathodoluminescence (CL) and electron paramagnetic resonance (EPR) spectroscopic study of quartz from the uranium-mineralized Athabasca Basin. CL imaging not only distinguishes detrital quartz grains from their secondary overgrowths but also is able to differentiate two generations of overgrowths in the Athabasca sandstones. Moreover, the Athabasca quartz samples are characterized by three types of bright CL: 1) haloes around U- and Th-bearing mineral inclusions, 2) patches associated with U-bearing minerals in matrices or pores and 3) continuous rims in samples with or without any visible U-bearing minerals. These three types of bright CL are all of constant widths of ~35-45 Ým, indicative of bombardments of alpha particles emitted from the 238U, 235U and 232Th decay series. CL spectral analyses show that the radiation damaged areas, relative to their undamaged hosts, are characterized by intense but broad emission bands at ~350 nm and 620-650 nm. <p>Detailed EPR measurements of the Athabasca quartz samples revealed six paramagnetic defects: one oxygen vacancy center (E1'), three silicon vacancy hole centers (O23¡V/H+(I), O23¡V/H+(II) and O23¡V/M+) and two O2¡V peroxy centers. Moreover, dissolution experiments using concentrated HF showed that that the silicon vacancy hole centers and the peroxy centers are concentrated in the radiation-damaged rims/fractures, whereas the oxygen vacancy center (E1') is evenly distributed in quartz grains. CL and EPR data of quartz samples after isochronal annealing experiments suggest that the silicon vacancy hole centers and the peroxy centers are most likely responsible for the characteristic ultraviolet CL and the red CL, respectively. <p>CL haloes in detrital quartz grains are ubiquitous in the Athabasca sandstones. CL patches are also widespread but are best developed in altered sandstones close to the unconformity or faults/fractures. Continuous CL rims, however, are more restricted in occurrences and are best developed at the high-grade Cigar Lake and McArthur River deposits, where they are restricted to lithological boundaries and faults and are pervasively developed in mineralized samples and associated alteration haloes close to the unconformity. At the Key Lake deposit, continuous rims occur only in mineralized samples close to the unconformity. Continuous CL rims are absent in basement rocks below mineralization, including those at the Cigar Lake and McArthur River deposits. The occurrence of radiation damages in Athabasca quartz have also been confirmed by detailed EPR measurements, which are significantly more sensitive than CL imaging. <p>Continuous CL rims on Athabasca quartz grains most likely record bombardments of alpha particles emitted from U-bearing mineralization fluids. Therefore, their associations with the unconformity, lithological boundaries and faults provide direct evidence for those structures being the pathways for mineralization fluids. The exclusive occurrence of continuous CL rims on detrital quartz grains and the abundance of U-bearing minerals in both generations of overgrowths suggest that U mineralization must have commenced during early diagenesis and continued during the formation of overgrowths. The absence of significant radiation damages in altered basement rocks supports the hypothesis that the basement was not a major source for uranium mineralization in the Athabasca basin. The common occurrence of CL haloes in euhedral quartz grains and CL patches associated with U-bearing minerals in faults, fractures and voids provide further (visual) evidence for late remobilization of uranium.

No description available.

No description available.

This study measures the electron-induced luminescence (cathodoluminescence) for various samples of fused silica. With a band gap of ~8.9 eV, visible and near-IR (NIR) luminescence occurs only if there are states (localized defect or trap states) within the forbidden band gap for electrons to occupy. A model is presented based on the electronic band structure and defect density of states—used to explain electron transport in highly disordered insulating materials—which has been extended to describe the relative cathodoluminescent intensity and spectral bands as a function of incident beam energy and current density, sample temperatures, and emitted photon wavelength. Tests were conducted on two types of disordered SiO2 samples, the first type containing two variations: (i) thin (~60 nm) coatings on reflective metal substrates, and (ii) ~80 μm thick bulk samples. Luminescence was measured using a visible range SLR CCD still camera, a VIS/NIR image-intensified video camera, a NIR video camera, and a UV/VIS spectrometer. Sample temperature was varied from ~295 K to 40 K. The results of these tests were fit with the proposed model using saturation dose rate and mean shallow trap energy as fitting parameters and are summarized below. First, each incident energy has a corresponding penetration depth, or range, which determines the fraction of energy absorbed in the material. In the thinner samples, the range exceeds the thickness of the sample; therefore, the intensity decreases with increasing energy. However, for the thicker samples, the range is less than the sample thickness and the intensity increases linearly with incident energy. Next, at low current densities, luminescent intensity is linearly proportional to incident current density through the dose rate. At very high current densities, saturation is observed. Finally, the overall luminescent intensity increased exponentially as T decreased, until reaching an optimum temperature, where it falls off to zero (as the model predicts). The spectra show four distinct bands of emitted photon wavelengths, corresponding to four distinct energy distributions of defect states within the band gap, each behaving differently with temperature. The response of each band to temperature is indicative of the extent to which it is filled.

The spectral range of quaternary AlGaInN/AlGaN MQWs extends from UV to IR. Nitride-based green and blue LEDs reveal a high efficiency for the further application. Integrating LEDs of three element colors can perform white light. The optical properties of GaN MQWs are very sensitive to the growth conditions of MQWs. The ununiformity is not fabrication desired but needs to prevent, which is necessary to understand and to precisely control through its growth condition for manufacture the LED. In this work the sample has a luminescence varied from orange to purple across the whole wafer. In this work, the correlations between optical and structural properties in these samples have been studied by means of Transmission Electron Microscopy (TEM), energy dispersive X-ray spectrometry (EDS), and cathodoluminescence (CL) measurements.

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 211-235). Also available for download via the World Wide Web; free to University of Oregon users.