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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Exaltation de l'émission dans le proche infrarouge par des antennes plasmoniques : nanotubes de carbone et centres G dans le silicium. / Photoluminescence enhancement in the near infrared using plasmonic antennas : carbon nanotubes and G-centers in silicon.

Beaufils, Clément 10 May 2019 (has links)
L'objectif général de cette thèse était d'exalter l'émission dans le proche infrarouge en utilisant des antennes plasmoniques. Les antennes plasmoniques permettent de modifier la dynamique de désexcitation ainsi que le diagramme d'émission d'un émetteur; ces deux aspects permettent donc d'améliorer/exalter la photoluminescence par rapport à un émetteur non couplé à une antenne. Au cours de cette thèse, deux émetteurs ont été étudiés : les nanotubes de carbone et les centres G dans le silicium.Les antennes plasmoniques sont, par exemple, des nanoparticules métalliques. Ainsi, dans un premier temps, nous avons étudié les propriétés de diffusion de nanoparticules métalliques. Ceci a permis de développer une technique permettant de déposer des nanoparticules uniques sur un substrat. La caractérisation optique de diverses nanoparticules déposées sur divers substrats fut réalisée par des mesures de spectres de diffusion. Des études en polarisation sur le signal excitateur ainsi que sur le signal diffusé ont permis de sonder l'origine des résonances plasmoniques apparaissant dans les spectres de diffusion. Les influences de la température et du substrat sur les spectres de diffusion ont aussi été étudiées.Dans une deuxième partie, nous nous sommes intéressés à un premier émetteur dans le proche infrarouge : les nanotubes de carbone semi-conducteurs. Nous avons caractérisé la photoluminescence d'un ensemble de nanotubes puis d'uniques nanotubes. La photoluminescence d'un nanotube de carbone unique est caractérisée par un faiblement rendement radiatif (de l'ordre du %) ce qui implique que, dans notre montage expérimental, l'émission par un unique nanotube est à la limite de détectabilité. Afin d’obtenir des applications optiques viables à base de nanotubes de carbone, nous avons essayé d'exalter leur photoluminescence grâce à des antennes plasmoniques. Nous avons donc déposé des nanoparticules métalliques au-dessus d’une couche de nanotubes de carbone. Nous avons observé ponctuellement l'exaltation de la photoluminescence, mais cette exaltation cessait sur des durées de l'ordre de la minute.Enfin, nous avons étudié un deuxième émetteur dans le proche infrarouge : les centres G dans le silicium. La caractérisation optique d'un ensemble de centre G a été réalisé. Le spectre d'émission a été mesuré et analysé quantitativement. Le temps de vie du centre G a aussi été mesuré pour la première fois. Ces deux types d'études (spectrales et temporelles) ont aussi été réalisées à diverses températures afin de sonder la dynamique de désexcitation des centres G. La saturation d'un ensemble de centres G a aussi été étudiée quantitativement. Enfin, nous avons réalisé des mesures laissant penser que le régime du centre G unique est presque atteint. L'exaltation de l'émission des centres G par des antennes plasmoniques n'a pas pu être étudiée par manque de temps. / The goal of this work was to enhance the photoluminescence in the near infrared using plasmonic antennas. Plasmonic antennas can modify both the recombination dynamics and the emission diagram; these two aspects can thus be used to enhance the photoluminescence of an emitter in comparison to an emitter not coupled with an antenna. During this thesis, two emitters were studied: carbon nanotubes and G-centers in silicon.Plasmonic antennas can be metallic nanoparticles for instance. Thus, we first studied the scattering properties of metallic nanoparticles. During this study, we developed a technique to deposit single nanoparticles on a substrate. The optical characterization of several nanoparticles on different substrates was realized through scattering spectrum measurements. Polarization studies on both the excitation light and the emitted light were realized in order to analyze the origin of plasmonic resonances in the scattering spectrum. The influence of the temperature and the substrate on the scattering spectrums was also investigated.Secondly, we looked into a first near infrared emitter: semi-conducting carbon nanotubes. We characterized the photoluminescence from an assembly of carbon nanotubes and then from single carbon nanotubes. The photoluminescence of a single carbon nanotube is characterized by a low quantum yield (typically, a few %) which implied, in our experimental setup, that the emission from a single nanotube is at the limit of detectability. In order to propose viable optical applications based on carbon nanotubes, we tried to enhance their photoluminescence with plasmonic antennas. We thus deposited metallic nanoparticles on top of a layer of carbon nanotubes. We occasionally observed some enhancements, but this typically ceased in less than a minute.Finally, we studied a second emitter in the near infrared: the G-centers in silicon. The optical characterization was realized. The emission spectrum was measured and quantitatively analyzed. The lifetime of the G-center was measured for the first time. These two studies (spectrally resolved and temporally resolved) were also realized for different temperatures in order to characterize the recombination dynamics of the G-centers. The saturation of an assembly of G-centers was also quantitatively studied. We also realized measurements suggesting that the single G-center regime has nearly been achieved. The enhancement of the photoluminescence of G centers with plasmonic antennas was not realized due to lack of time.
2

Extrinsic Quantum Centers in Silicon for Nanophotonics and Quantum Applications

Herzig, Tobias 21 June 2022 (has links)
Quantenzentren in Kristallgittern spielen als sogenannte Festkörper-Qubits eine entscheidende Rolle für die Entwicklung der zweiten Quantenrevolution. Das G-Zentrum in Silizium kann hierfür einen wesentlichen Beitrag leisten, da es sich CMOS-kompatibel und damit skalierbar herstellen lässt, es eine scharfe Nullphononenlinie im Bereich der optischen Telekommunikation besitzt und ODMR-aktiv ist. Dies macht es zu einem geeigneten Kandidaten für die Entwicklung photonischer Mikrochips, auf denen Quantentechnologien und Lichtwellenleitung durch eine Spin-Photon-Schnittstelle miteinander verknüpft werden, um somit alle Kriterien zum Aufbau eines Quantennetzwerkes zu erfüllen. In der vorliegenden Arbeit werden G-Zentren durch niederenergetische und räumlich-selektive Ionen-Implantation hergestellt und mittels Photolumineszenz-Spektroskopie und Magnetresonanzmessungen auf ihre optischen und quantenphysikalischen Eigenschaften untersucht. Anhand umfangreicher temperaturabhängiger Ensemble-Messungen in reinem Silizium werden offene Fragen zum Sättigungsverhalten, der Rekombinationsdynamik und der Verschiebung bzw. Verbreiterung der Nullphononenlinie geklärt und die ersten Zerfallszeit-Messungen des angeregten Zustandes des Defektes vorgestellt. Durch die Verwendung von SOI-Proben in Kombination mit niederenergetischer Ionen-Implantation wird weiterhin die erste, jemals in Silizium isolierte Einzelphotonenquelle hergestellt und durch zahlreiche Polarisations- und Korrelationsmessungen als solche identifiziert. Durch die Einzelphotonenmessung erfolgt zusätzlich eine erste Abschätzung der Quanteneffizienz der G-Zentren und die Messung der Lebensdauer des isolierten angeregten Zustandes. Um den Quantenzustand der G-Zentren mittels Mikrowellenfeld manipulieren und sowohl optische als auch elektronisch auslesen zu können, wird ein experimenteller Aufbau beschrieben, mit dem die magnetische Resonanz der G-Zentren in einer SOI-Probe temperaturabhängig bis in den kryogenen Bereich detektiert werden kann. Nach den ersten manuellen Testmessungen wird der Versuchsaufbau durch neue Steuergeräte und eine Automatisierung weiter optimiert, um damit umfangreiche Messungen bei T = 40K und Raumtemperatur durchzuführen. Dabei wird eine mikrowellenabhängige Manipulation der Photolumineszenz der G-Zentren beobachtet, welche mit dem detektierten Photostrom korreliert ist. Die Manipulation der Photolumineszenz wird hauptsächlich auf eine Veränderung der Ladungsträgerdichte aufgrund anderer spinabhängiger Rekombinationszentren zurückgeführt, welche sich an den Grenzflächen des SOI-Schichtstapels bilden. Ideen, um den Einfluss der G-Zentren durch Unterdrückung der anderen Rekombinationszentren zu erhöhen, werden diskutiert.:Bibliografische Beschreibung Referat Abstract Zusammenfassung der Dissertation Contents List of Figures List of Tables Abbreviations 1 Introduction and motivation 1.1 Demand for silicon photonics and quantum technologies 1.2 Description and aim of the project 1.3 Outline 2 Solid-state and optical properties of silicon 2.1 Crystal properties 2.1.1 Structure 2.1.2 Lattice vibrations 2.1.3 Debye-Waller factor 2.1.4 Energy bands 2.2 Defects and doping in silicon 2.2.1 Intrinsic and extrinsic point defects 2.2.2 Line, area and volume defects 2.2.3 Doping 2.3 Luminescence from silicon 2.3.1 Optical properties of bulk silicon 2.3.2 Non-linear effects in silicon 2.3.3 Dislocation loops 2.3.4 Quantum confinement effects 2.3.5 Rare-Earth (Erbium) doping 2.3.6 Light emitting defects in silicon 2.4 G centers in silicon 2.4.1 Structural properties and creation of G centers 2.4.2 Optical properties and applications of G centers 3 Solid-state quantum technologies 3.1 Ion implantation for defect engineering 3.1.1 High-energy accelerator “Lipsion” 3.1.2 100 kV Microbeam 3.2 Quantum optics 3.2.1 Properties of single photons 3.2.2 Photoluminescence and single-photon measurements 3.2.3 Applications of single-photon sources - quantum key distribution 3.3 Quantum computing 3.3.1 Basic principle 3.3.2 Photonic qubits 3.3.3 Solid-state qubits 4 Optical properties of an ensemble of G centers in silicon 4.1 Experiment description and basic properties 4.1.1 Sample fabrication 4.1.2 Optical spectroscopy 4.1.3 PL response of different defect densities 4.1.4 Photoluminescence excitation measurement 4.1.5 Saturation behavior 4.2 Temperature-dependent photoluminescence spectroscopy 4.2.1 Thermal redshift 4.2.2 ZPL broadening 4.2.3 Temperature-dependent PL intensity 4.2.4 Temperature-dependent lifetime and decay rate 4.3 Recombination dynamics 4.3.1 Spectrally selective recombination dynamics 4.3.2 Lifetime and defect density 4.3.3 Phonon-assisted recombination model 5 G centers as single-photon sources in silicon 5.1 Experimental description 5.1.1 Sample fabrication 5.1.2 Optical spectroscopy 5.2 Evidence of a single-photon source 5.2.1 Autocorrelation study 5.2.2 Photodynamics 5.2.3 PL polarization 5.3 Properties of single photons from G centers 5.3.1 ZPL shift 5.3.2 Saturation and stability 5.3.3 Lifetime of an isolated G center 5.3.4 Estimation of the quantum efficiency 6 Optical and photoelectric readout of G centers in silicon 6.1 Setup 6.1.1 Sample preparation 6.1.2 Circuit board and cryostat 6.1.3 Measuring and control devices 6.1.4 PL spectroscopy 6.2 Manual ODMR and PDMR at cryogenic temperature 6.3 Automated PDMR measurements 6.3.1 Spectrum analysis 6.3.2 Etiology 6.3.3 Voltage dependence 6.3.4 Temperature dependence 6.3.5 Laser dependence 6.3.6 Magnetic field dependence 6.4 Automated PDMR and ODMR at cryogenic temperature 6.5 Discussion 6.5.1 Microwave dielectric heating in silicon 6.5.2 Spin-dependent recombination centers in Si and Si/SiO2 interfaces 6.6 Conclusion 7 Summary and outlook Bibliography Danksagung Wissenschaftlicher Werdegang Selbstständigkeitserklärung Erklärung für die Bibliothek / Quantum centers in crystal lattices can form so-called solid-state qubits that play a crucial role for the progress of the second quantum revolution. The G center in silicon can make a significant contribution to this, since it can be fabricated in a CMOS compatible and thus scalable way, it has a sharp zero-phonon line in the optical telecommunication range, and it is ODMR active. This makes it a suitable candidate for the development of photonic microchips, where quantum technologies and optical waveguides are linked by a spin-photon interface, thus fulfilling all the criteria to build a quantum network. In the present work, G centers are fabricated by low-energy and spatially-selective ion implantation and their optical and quantum physical properties are investigated by photoluminescence spectroscopy and magnetic resonance measurements. Using extensive temperature-dependent ensemble measurements in pure silicon, open questions on saturation behavior, recombination dynamics, and zero-phonon line shift as well as broadening are clarified, and the first decay time measurements of the excited state of this defect are presented. By using SOI samples in combination with low-energy ion implantation, the first single-photon source ever isolated in silicon is further fabricated and identified as such by extensive polarization and correlation measurements. The single-photon measurement additionally provides a first estimation of the quantum efficiency of the G centers and the measurement of the lifetime of the isolated excited state. In order to manipulate the quantum state of the G centers by means of a microwave field and to enable an optical as well as an electronical readout, an experimental setup is designed and assembled that allows the temperature-dependent detection of magnetic resonances of G centers in a SOI sample down to the cryogenic range. After the first manual test measurements, the experimental setup is further optimized by new control devices and process automation to allow extensive measurements at T = 40K and room temperature. A microwave-dependent manipulation of the photoluminescence of the G centers is observed, which is correlated with the detected photocurrent. The manipulation of the photoluminescence is mainly attributed to a change in the charge carrier density due to other spin-dependent recombination centers that form at the interfaces of the SOI layer stack. Ideas to increase the influence of the G centers by suppressing the other recombination centers are discussed.:Bibliografische Beschreibung Referat Abstract Zusammenfassung der Dissertation Contents List of Figures List of Tables Abbreviations 1 Introduction and motivation 1.1 Demand for silicon photonics and quantum technologies 1.2 Description and aim of the project 1.3 Outline 2 Solid-state and optical properties of silicon 2.1 Crystal properties 2.1.1 Structure 2.1.2 Lattice vibrations 2.1.3 Debye-Waller factor 2.1.4 Energy bands 2.2 Defects and doping in silicon 2.2.1 Intrinsic and extrinsic point defects 2.2.2 Line, area and volume defects 2.2.3 Doping 2.3 Luminescence from silicon 2.3.1 Optical properties of bulk silicon 2.3.2 Non-linear effects in silicon 2.3.3 Dislocation loops 2.3.4 Quantum confinement effects 2.3.5 Rare-Earth (Erbium) doping 2.3.6 Light emitting defects in silicon 2.4 G centers in silicon 2.4.1 Structural properties and creation of G centers 2.4.2 Optical properties and applications of G centers 3 Solid-state quantum technologies 3.1 Ion implantation for defect engineering 3.1.1 High-energy accelerator “Lipsion” 3.1.2 100 kV Microbeam 3.2 Quantum optics 3.2.1 Properties of single photons 3.2.2 Photoluminescence and single-photon measurements 3.2.3 Applications of single-photon sources - quantum key distribution 3.3 Quantum computing 3.3.1 Basic principle 3.3.2 Photonic qubits 3.3.3 Solid-state qubits 4 Optical properties of an ensemble of G centers in silicon 4.1 Experiment description and basic properties 4.1.1 Sample fabrication 4.1.2 Optical spectroscopy 4.1.3 PL response of different defect densities 4.1.4 Photoluminescence excitation measurement 4.1.5 Saturation behavior 4.2 Temperature-dependent photoluminescence spectroscopy 4.2.1 Thermal redshift 4.2.2 ZPL broadening 4.2.3 Temperature-dependent PL intensity 4.2.4 Temperature-dependent lifetime and decay rate 4.3 Recombination dynamics 4.3.1 Spectrally selective recombination dynamics 4.3.2 Lifetime and defect density 4.3.3 Phonon-assisted recombination model 5 G centers as single-photon sources in silicon 5.1 Experimental description 5.1.1 Sample fabrication 5.1.2 Optical spectroscopy 5.2 Evidence of a single-photon source 5.2.1 Autocorrelation study 5.2.2 Photodynamics 5.2.3 PL polarization 5.3 Properties of single photons from G centers 5.3.1 ZPL shift 5.3.2 Saturation and stability 5.3.3 Lifetime of an isolated G center 5.3.4 Estimation of the quantum efficiency 6 Optical and photoelectric readout of G centers in silicon 6.1 Setup 6.1.1 Sample preparation 6.1.2 Circuit board and cryostat 6.1.3 Measuring and control devices 6.1.4 PL spectroscopy 6.2 Manual ODMR and PDMR at cryogenic temperature 6.3 Automated PDMR measurements 6.3.1 Spectrum analysis 6.3.2 Etiology 6.3.3 Voltage dependence 6.3.4 Temperature dependence 6.3.5 Laser dependence 6.3.6 Magnetic field dependence 6.4 Automated PDMR and ODMR at cryogenic temperature 6.5 Discussion 6.5.1 Microwave dielectric heating in silicon 6.5.2 Spin-dependent recombination centers in Si and Si/SiO2 interfaces 6.6 Conclusion 7 Summary and outlook Bibliography Danksagung Wissenschaftlicher Werdegang Selbstständigkeitserklärung Erklärung für die Bibliothek

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