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Réalisation de couches minces nanocomposites par un procédé original couplant la pyrolyse laser et la pulvérisation magnétron : application aux cellules solaires tout silicium de troisième génération / Elaboration of nanostructured thin films by laser pyrolysis and magnetron sputtering combined process : application to all silicon third generation solar cellsKintz, Harold 17 December 2013 (has links)
Ce travail porte sur la synthèse de couches minces de nanoparticules de silicium (np-Si) encapsulées dans une matrice diélectrique en vue d’une application en tant que couche active pour les cellules solaires de 3ème génération. La technique utilisée pour la synthèse des np-Si est la pyrolyse laser. Cette technique nous a permis d’obtenir des np-Si cristallines d’environ 5 nm de diamètre avec une distribution en taille étroite. Par ailleurs, l’utilisation de gaz précurseurs spécifiques (PH₃, B₂H₆) dans le mélange réactionnel a rendu possible le dopage (type n ou p) des np-Si. Le dopage effectif des np-Si a pu être mis en évidence par des mesures de résonance paramagnétique électronique (RPE). Des films de np-Si seules ont pu être déposés in-situ via la création d’un jet supersonique de gaz contenant les particules de silicium. Les caractérisations optoélectroniques de ces couches ont montré un effet de confinement quantique fort au sein de films, garantissant ainsi un élargissement important du gap du silicium de 1.12 eV (pour le silicium massif) à environ 2 eV (pour les np-Si) ; prérequis indispensable pour réaliser une cellule tandem tout silicium. Des mesures de résistivité sur ces films ont permis de confirmer l’activité des dopants au sein des np-Si. Pour les np-Si dopées au phosphore une diminution de la résistivité de plus de 5 ordres de grandeurs par rapport au np-Si intrinsèques a été observée. Le couplage entre la pyrolyse laser et la pulvérisation magnétron via notre dispositif original de synthèse s’est révélé parfaitement adapté à l’élaboration de couches minces nanocomposites np-Si/SiO₂. Un comportement de type diode a pu être mis en évidence sur une jonction constituée par la superposition d’une couche nanocomposites (type n) sur un substrat de silicium massif (type p). Au-delà de la simple application au photovoltaïque, le procédé couplé, largement éprouvé et optimisé au cours de ce travail de thèse, pourrait permettre la réalisation d’une multitude de couches nanocomposites différentes, puisque la nature chimique des particules et de la matrice peuvent être choisies indépendamment. / This work focuses on the synthesis of thin films composed of silicon nanoparticles (np- Si) embedded in a dielectric matrix for application as an active layer for the third generation solar cells. The technique used for the synthesis of np-Si is the laser pyrolysis. This technique allowed us to obtain 5 nm cristalline np -Si with a narrow size distribution. Furthermore, the use of specific precursor gases (PH₃, B₂H₆) in the reaction mixture enables doping (n or p -type) of np -Si. Effective np -Si doping has been demonstrated by measurements of electron paramagnetic resonance (EPR). Films made of np-Si only, have been deposited in situ by creating a supersonic jet of gas containing the silicon particles. Optoelectronic characterization of these layers showed a strong quantum confinement effect in films, thus ensuring a significant widening of the gap of 1.12 eV silicon (for bulk silicon) to about 2 eV (np -Si); which is an essential prerequisite to achieve a silicon tandem cell. Resistivity measurements on these films have confirmed the dopants activity in the np -Si. For np -Si doped with phosphorus, a significant decrease of the resistivity of more than five orders of magnitude compared to the intrinsic np -Si was observed. Coupling between laser pyrolysis and magnetron sputtering through our original synthesis device proved to be perfectly suited for the elaboration of nanocomposite thin films np-Si/SiO₂. A diode-type behavior has been highlighted on a junction formed by the superposition of a nanocomposite layer (n-type) on a bulk silicon substrate (p-type ). Beyond the simple application to photovoltaics , the coupled process, widely used and optimized during this work could allow the production of a multitude of different nanostructured layers , since the chemical nature of the particles and the matrix can be chosen independently.
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Optical properties of InAs/InP nanowire heterostructures / Propriétés optiques des InAs/InP hétérostructures de nanofilsAnufriev, Roman 22 November 2013 (has links)
Ce travail de thèse porte sur l’étude des propriétés optiques de nanofils InP et d’hétérostructures nanofils InAs/InP épitaxiés sur substrat silicium. Ce travail de thèse a été réalisé principalement dans le cadre du projet ANR «INSCOOP». / This thesis is focused upon the experimental investigation of optical properties of InAs/InP NW heterostructures by means of photoluminescence (PL) spectroscopy. First, it was demonstrated that the host-substrate may have significant impacts on the optical properties of pure InP NWs, as due to the strain, created by the difference in the LTECs of the NWs and the host-substrate, as due to some other surface effects. Next, the optical properties of such nanowire heterostructures as quantum rod (QRod) and radial quantum well (QWell) NWs were investigated. The features of obtained spectra were explained using theoretical simulation of similar NW heterostructures. The polarization properties of single InP NWs, InAs/InP QWell-NWs, InAs/InP QRod-NWs and ensemble of the InAs well ordered NWs were studied at different temperatures. Further, we report on the evidences of the strain-induced piezoelectric field in WZ InAs/InP QRod-NWs. Finally, PL QE of NW heterostructures and their planar analogues are measured by means of a PL setup coupled to an integrating sphere. In general, the obtained knowledge of the optical and mechanical properties of pure InP NWs and InAs/InP NW heterostructures will improve understanding of the electrical and mechanical processes taking place in semiconductor NW heterostructures and will serve for the fabrication of future nanodevice applications.
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Design and manufacture of nanometre-scale SOI light sourcesBogalecki, Alfons Willi 11 January 2010 (has links)
To investigate quantum confinement effects on silicon (Si) light source electroluminescence (EL) properties like quantum efficiency, external power efficiency and spectral emission, thin Si finger junctions with nanometre-scale dimensions were designed and manufactured in a fully customized silicon-on-insulator (SOI) semiconductor production technology. Since commonly available photolithography is unusable to consistently define and align nanometre-scale line-widths accurately and electron-beam lithography (EBL) by itself is too time-expensive to expose complete wafers, the wafer manufacturing process employed a selective combination of photolithography and EBL. The SOI wafers were manufactured in the clean-rooms of both the Carl and Emily Fuchs Institute for Microelectronics (CEFIM) at the University of Pretoria (UP) and the Georgia Institute of Technology’s Microelectronic Research Centre (MiRC), which made a JEOL JBX-9300FS electron-beam pattern generator (EPG) available. As far as is known this was the first project in South Africa (and possibly at the MiRC) that employed EBL to define functional nanometre-scale semiconductor devices. Since no standard process recipe could be employed, the complete design and manufacturing process was based on self-obtained equipment characterization data and material properties. The manufacturing process was unprecedented in both the CEFIM and MiRC clean-rooms. The manufacture of nanometre-scale Si finger junctions not only approached the manufacturing limits of the employed processing machinery, but also had to overcome undesirable physical effects that in larger-scale semiconductor manufacture usually are negligible. The device design, mask layout and manufacturing process therefore had to incorporate various material, equipment limitation and physical phenomena like impurity redistribution occurring during the physical manufacturing process. Although the complicated manufacturing process allowed many unexpected problems to occur, it was expected that at least the simple junction breakdown devices be functional and capable of delivering data regarding quantum confinement effects. Although due to design and processing oversights only 29 out of 505 measured SOI light sources were useful light emitters, the design and manufacture of the SOI light sources was successful in the sense that enough SOI light sources were available to conduct useful optical characterization measurements. In spite of the fact that the functional light sources did not achieve the desired horizontal (width) confinement, measured optical spectra of certain devices indicate that vertical (thickness) confinement had been achieved. All spectrometer-measured thickness-confined SOI light sources displayed a pronounced optical power for 600 nm < λ < 1 μm. The SOI light source with the highest optical power output emitted about 8 times more optical power around λ = 850 nm than a 0.35 μm bulk-CMOS avalanche light-source operating at the same current. Possible explanations for this effect are given. It was shown that the buried oxide (BOX) layer in a SOI process could be used to reflect about 25 % of the light that would usually be lost to downward radiation back up, thereby increasing the external power efficiency of SOI light sources. This document elaborates on the technical objectives, approach, chip and process design, physical wafer manufacture, production process control and measurement of the nanometre-scale SOI light sources. Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted
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Spectroscopie linéaire et ultra-rapide de nanoparticules métalliques : de l’ensemble au nano-objet individuel / Linear and ultra-fast spectroscopy of metallic nanoparticles : from ensemble to individual nano-objectsJuvé, Vincent 27 September 2011 (has links)
En passant de l’état massif à la nanoparticule les matériaux métalliques voient certaines de leurs caractéristiques modifiées de manière notable comme par exemple les propriétés optiques avec l’apparition d’une résonance dans le spectre optique, la Résonance Plasmon de Surface Localisée (RPSL) responsable du changement de couleur des nanoparticules métalliques. Les propriétés vibrationnelles et thermiques de nanoparticules métalliques ont été étudiées à l’aide d’une technique de Spectroscopie Femtoseconde. Nous avons montré qu’il était possible d’exciter et de détecter optiquement des fréquences de vibrations mécaniques dans le domaine térahertz pour des nanoparticules de platine composées de moins de cent atomes. D’autre part l’augmentation des effets dus aux interfaces a été mis en évidence sur les propriétés thermiques de nanoparticules d’or et d’argent. La résistance thermique à l’interface, résistance de Kapitza, voit son rôle augmenter lors du transfert thermique à l’échelle nanométrique. Une corrélation entre les valeurs mesurées et les impédances acoustiques des matériaux composants les interfaces a été mise en évidence. Nous avons aussi montré qu’elle augmente quand la température diminue de 300K à 70K. Les propriétés optiques de nanoparticules non sphériques ont été étudiées à l’aide de la Spectroscopie à Modulation Spatiale. Cette technique a permis de repérer puis de caractériser des nano-bâtonnets d’or individuels. Nous avons montré que la largeur spectrale de la RPSL est fortement dépendante de la géométrie des nanoparticules (diamètre et longueur). Cette double dépendance n’est pas prédite par les modèles classiques ou quantique existants / The size reduction of metals, from bulk to nanoparticles, induces significant modifications of their properties. For instance, the optical properties evolve and a new resonance, the localized surface plasmon resonance, appears in the optical spectrum and is responsible for the change of colors of metallic nanoparticles. This work is focused on studies of metals’ properties at the nanometric scale. In the first part, the vibrational and thermal properties are studied with a femtosecond spectroscopy technique. It is shown that it is possible to excite and detect optically vibrational frequencies in the terahertz domain by studying platinum nanoparticles formed by less than 100 atoms. The study of the thermal properties of the metallic nanoparticles (gold and silver) has shown that the boundary effect increases. This thermal boundary resistance, known as the Kapitza resistance, plays a dominant role in the heat transfer at the nanometric scale. A correlation between the experimental values of the thermal boundary resistance and the acoustic impedances of the boundary’s materials has been found. We have also shown that the Kapitza resistance is a decreasing function of the temperature in the 70-300K range. In the second part, the effect of the size reduction on the optical properties of non-spherical nanoparticles is observed. The Spatial Modulation Spectroscopy technique is used in order to locate and study individual gold nanorods. It is shown that the two geometrical parameters (the length and the diameter) of the nanorods influence the spectral linewidth of the localized surface plasmon resonance. This effect is not predicted by existing classical or quantum models
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Simulation of the electron transport through silicon nanowires and across NiSi2-Si interfacesFuchs, Florian 25 April 2022 (has links)
Die fortschreitenden Entwicklungen in der Mikro- und Nanotechnologie erfordern eine solide Unterstützung durch Simulationen. Numerische Bauelementesimulationen waren und sind dabei
unerlässliche Werkzeuge, die jedoch zunehmend an ihre Grenzen kommen. So basieren sie auf Parametern, die für beliebige Atomanordnungen nicht verfügbar sind, und scheitern für stark verkleinerte Strukturen infolge zunehmender Relevanz von Quanteneffekten.
Diese Arbeit behandelt den Transport in Siliziumnanodrähten sowie durch NiSi2-Si-Grenzflächen. Dichtefunktionaltheorie wird dabei verwendet, um die stabile Atomanordnung und alle für den elektronischen Transport relevanten quantenmechanischen Effekte zu beschreiben.
Bei der Untersuchung der Nanodrähte liegt das Hauptaugenmerk auf der radialen Abhängigkeit der elektronischen Struktur sowie deren Änderung bei Variation des Durchmessers. Dabei zeigt sich, dass der Kern der Nanodrähte für den Ladungstransport bestimmend ist. Weiterhin kann ein Durchmesser von ungefähr 5 nm identifiziert werden, oberhalb dessen die Zustandsdichte im Nanodraht große Ähnlichkeiten mit jener des Silizium-Volumenkristalls aufweist und der Draht somit zunehmend mit Näherungen für den perfekt periodischen Kristall beschrieben werden kann.
Der Fokus bei der Untersuchung der NiSi2-Si-Grenzflächen liegt auf der Symmetrie von Elektron- und Lochströmen im Tunnelregime, welche für die Entwicklung von rekonfigurierbaren Feldeffekttransistoren besondere Relevanz hat. Verschiedene NiSi2-Si-Grenzflächen und Verzerrungszustände werden dabei systematisch untersucht. Je nach Grenzfläche ist die Symmetrie dabei sehr unterschiedlich und zeigt auch ein sehr unterschiedliches Verhalten bei externer Verzerrung.
Weiterhin werden grundlegende physikalische Größen mit Bezug zu NiSi2-Si-Grenzflächen betrachtet. So wird beispielsweise die Stabilität anhand von Grenzflächen-Energien ermittelt. Am stabilsten sind {111}-Grenzflächen, was deren bevorzugtes Auftreten in Experimenten erklärt. Weitere wichtige Größen, deren Verzerrungsabhängigkeit untersucht wird, sind die Schottky-Barrierenhöhe, die effektive Masse der Ladungsträger sowie die Austrittsarbeiten von NiSi2- und
Si-Oberflächen.
Ein Beitrag zur Modellentwicklung numerischer Bauelementesimulationen wird durch einen Vergleich zwischen den Ergebnissen von Dichtefunktionaltheorie-basierten Transportrechnungen und denen eines vereinfachten Models basierend auf der Wentzel-Kramers-Brillouin-Näherung geliefert. Diese Näherung ist Teil vieler numerischer Bauelementesimulatoren und erlaubt die Berechnung des Tunnelstroms basierend auf grundlegenden physikalischen Größen. Der Vergleich
ermöglicht eine Evaluierung des vereinfachten Models, welches anschließend genutzt wird, um den Einfluss der grundlegenden physikalischen Größen auf den Tunneltransport zu untersuchen.:Index of Abbreviations
1. Introduction
2. Silicon Based Devices and Silicon Nanowires
2.1. Introduction
2.2. The Reconfigurable Field-effect Transistor
2.2.1. Design and Functionality
2.2.2. Fabrication
2.3. Overview Over Silicon Nanowires
2.3.1. Geometric Structure
2.3.2. Fabrication Techniques
2.3.3. Electronic Properties
3. Simulation Tools
3.1. Introduction
3.2. Electronic Structure Calculations
3.2.1. Introduction and Basis Functions
3.2.2. Density Functional Theory
3.2.3. Description of Exchange and Correlation Effects
3.2.4. Practical Aspects of Density Functional Theory
3.3. Electron Transport
3.3.1. Introduction
3.3.2. Scattering Theory
3.3.3. Wentzel-Kramers-Brillouin Approximation for a Triangular Barrier
3.3.4. Non-equilibrium Green’s Function Formalism
A. Radially Resolved Electronic Structure and Charge Carrier Transport in Silicon Nanowires
A.1. Introduction
A.2. Model System
A.3. Results and Discussion
A.4. Summary and Conclusions
A.5. Appendix A: Computational Details
A.6. Appendix B: Supplementary Material
A.6.1. Comparison of the Band Gap Between Relaxed and Unrelaxed SiNWs
A.6.2. Band Structures for Some of the Calculated SiNWs
A.6.3. Radially Resolved Density of States for Some of the Calculated SiNWs
B. Electron Transport Through NiSi2-Si Contacts and Their Role in Reconfigurable
Field-effect Transistors
B.1. Introduction
B.2. Model for Reconfigurable Field-effect Transistors
B.2.1. Atomistic Quantum Transport Model to Describe Transport Across the Contact Interface
B.2.2. Simplified Compact Model to Calculate the Device Characteristics
B.3. Results and Discussion
B.3.1. Characteristics of a Reconfigurable Field-effect Transistor
B.3.2. Variation of the Crystal Orientations and Influence of the Schottky Barrier
B.3.3. Comparison to Fabricated Reconfigurable Field-effect Transistors
B.4. Summary and Conclusions
B.5. Appendix: Supplementary Material
B.5.1. Band Structure and Density of States of the Contact Metal
B.5.2. Relaxation Procedure
B.5.3. Total Transmission Through Multiple Barriers
C. Formation and Crystallographic Orientation of NiSi2-Si Interfaces
C.1. Introduction
C.2. Fabrication and characterization methods
C.3. Model System and Simulation Details
C.4. Results and discussion
C.4.1. Atomic structure of the interface
C.4.2. Discussion of ways to modify the interface orientation
C.5. Summary
C.6. Appendix: Supplementary Material
D. NiSi2-Si Interfaces Under Strain: From Bulk and Interface Properties to Tunneling Transport
D.1. Introduction
D.2. Model System and Simulation Approach
D.3. Computational Details
D.3.1. Electronic Structure Calculations (Geometry Relaxations)
D.3.2. Electronic Structure Calculations (Electronic Structure)
D.3.3. Device Calculations
D.4. Tunneling Transport From First-principles Calculations
D.4.1. Evaluation of the Current
D.4.2. Isotropic Strain
D.4.3. Anisotropic Strain
D.5. Transport Related Properties and Effective Modeling Schemes
D.5.1. Schottky Barrier Height
D.5.2. Simplified Transport Model
D.5.3. Models for the Schottky Barrier Height
D.6. Summary and Conclusions
D.7. Appendix: Supplementary Material
D.7.1. Schottky Barriers of the {110} Interface Under Anisotropic Strain
D.7.2. Silicon Band Structure, Electric Field, and Number of Transmission Channels
D.7.3. k∥-resolved Material Properties
D.7.4. Evaluation of the Work Functions and Electron Affinities
D.7.5. Verification of the Work Function Calculation
4. Discussion
5. Ongoing Work and Possible Extensions
6. Summary
Bibliography
List of Figures
List of Tables
Acknowledgements
Selbstständigkeitserklärung
Curriculum Vitae
Scientific Contributions / The ongoing developments in micro- and nanotechnologies require a profound support from simulations. Numerical device simulations were and still are essential tools to support the device development. However, they gradually reach their limits as they rely on parameters, which are not always available, and neglect quantum effects for small structures.
This work addresses the transport in silicon nanowires and through NiSi2-Si interfaces. By using density functional theory, the atomic structure is considered, and all electron transport related quantum effects are taken into account.
Silicon nanowires are investigated with special attention to their radially resolved electronic structure and the corresponding modifications when the silicon diameter is reduced. The charge transport occurs mostly in the nanowire core. A diameter of around 5 nm can be identified, above which the nanowire core exhibits a similar density of states as bulk silicon. Thus, bulk approximations become increasingly valid above this diameter.
NiSi2-Si interfaces are studied with focus on the symmetry between electron and hole currents in the tunneling regime. The symmetry is especially relevant for the development of reconfigurable field-effect transistors. Different NiSi2-Si interfaces and strain states are studied systematically. The symmetry is found to be different between the interfaces. Changes of the symmetry upon external strain are also very interface dependent.
Furthermore, fundamental physical properties related to NiSi2-Si interfaces are evaluated. The stability of the different interfaces is compared in terms of interface energies. {111} interfaces are most stable, which explains their preferred occurrence in experiments. Other properties, whose strain dependence is studied, include the Schottky barrier height, the effective mass of the carriers, and work functions.
A contribution to the development of numerical device simulators will be given by comparing the results from density functional theory based transport calculations and a model based on the Wentzel-Kramers-Brillouin approximation. This approximation, which is often employed in numerical device simulators, offers a relation between interface properties and the tunneling transport. The comparison allows an evaluation of the simplified model, which is then used to investigate the relation between the fundamental physical properties and the tunneling transport.:Index of Abbreviations
1. Introduction
2. Silicon Based Devices and Silicon Nanowires
2.1. Introduction
2.2. The Reconfigurable Field-effect Transistor
2.2.1. Design and Functionality
2.2.2. Fabrication
2.3. Overview Over Silicon Nanowires
2.3.1. Geometric Structure
2.3.2. Fabrication Techniques
2.3.3. Electronic Properties
3. Simulation Tools
3.1. Introduction
3.2. Electronic Structure Calculations
3.2.1. Introduction and Basis Functions
3.2.2. Density Functional Theory
3.2.3. Description of Exchange and Correlation Effects
3.2.4. Practical Aspects of Density Functional Theory
3.3. Electron Transport
3.3.1. Introduction
3.3.2. Scattering Theory
3.3.3. Wentzel-Kramers-Brillouin Approximation for a Triangular Barrier
3.3.4. Non-equilibrium Green’s Function Formalism
A. Radially Resolved Electronic Structure and Charge Carrier Transport in Silicon Nanowires
A.1. Introduction
A.2. Model System
A.3. Results and Discussion
A.4. Summary and Conclusions
A.5. Appendix A: Computational Details
A.6. Appendix B: Supplementary Material
A.6.1. Comparison of the Band Gap Between Relaxed and Unrelaxed SiNWs
A.6.2. Band Structures for Some of the Calculated SiNWs
A.6.3. Radially Resolved Density of States for Some of the Calculated SiNWs
B. Electron Transport Through NiSi2-Si Contacts and Their Role in Reconfigurable
Field-effect Transistors
B.1. Introduction
B.2. Model for Reconfigurable Field-effect Transistors
B.2.1. Atomistic Quantum Transport Model to Describe Transport Across the Contact Interface
B.2.2. Simplified Compact Model to Calculate the Device Characteristics
B.3. Results and Discussion
B.3.1. Characteristics of a Reconfigurable Field-effect Transistor
B.3.2. Variation of the Crystal Orientations and Influence of the Schottky Barrier
B.3.3. Comparison to Fabricated Reconfigurable Field-effect Transistors
B.4. Summary and Conclusions
B.5. Appendix: Supplementary Material
B.5.1. Band Structure and Density of States of the Contact Metal
B.5.2. Relaxation Procedure
B.5.3. Total Transmission Through Multiple Barriers
C. Formation and Crystallographic Orientation of NiSi2-Si Interfaces
C.1. Introduction
C.2. Fabrication and characterization methods
C.3. Model System and Simulation Details
C.4. Results and discussion
C.4.1. Atomic structure of the interface
C.4.2. Discussion of ways to modify the interface orientation
C.5. Summary
C.6. Appendix: Supplementary Material
D. NiSi2-Si Interfaces Under Strain: From Bulk and Interface Properties to Tunneling Transport
D.1. Introduction
D.2. Model System and Simulation Approach
D.3. Computational Details
D.3.1. Electronic Structure Calculations (Geometry Relaxations)
D.3.2. Electronic Structure Calculations (Electronic Structure)
D.3.3. Device Calculations
D.4. Tunneling Transport From First-principles Calculations
D.4.1. Evaluation of the Current
D.4.2. Isotropic Strain
D.4.3. Anisotropic Strain
D.5. Transport Related Properties and Effective Modeling Schemes
D.5.1. Schottky Barrier Height
D.5.2. Simplified Transport Model
D.5.3. Models for the Schottky Barrier Height
D.6. Summary and Conclusions
D.7. Appendix: Supplementary Material
D.7.1. Schottky Barriers of the {110} Interface Under Anisotropic Strain
D.7.2. Silicon Band Structure, Electric Field, and Number of Transmission Channels
D.7.3. k∥-resolved Material Properties
D.7.4. Evaluation of the Work Functions and Electron Affinities
D.7.5. Verification of the Work Function Calculation
4. Discussion
5. Ongoing Work and Possible Extensions
6. Summary
Bibliography
List of Figures
List of Tables
Acknowledgements
Selbstständigkeitserklärung
Curriculum Vitae
Scientific Contributions
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Люминесцентные свойства и фотометрические характеристики наноструктур с квантовыми точками InP/ZnS : магистерская диссертация / Luminescent properties and photometric characteristics of nanostructures with InP/ZnS quantum dotsСавченко, С. С., Savchenko, S. S. January 2016 (has links)
В работе проведено исследование оптических характеристик коллоидных квантовых точек (КТ) InP/ZnS различных размеров (QD-1, QD-2, QD-3) и композитных наноструктур анодированного оксида алюминия (AAО) с КТ методами спектрофотометрии и люминесцентной спектроскопии.
Выполнен литературный обзор, касающийся электронных состояний в идеальном нанокристалле (НК), синтеза КТ на основе InP, использования НК для создания нанокомпозитов и расчёта цветовых характеристик излучателей. Описаны методики подготовки образцов и проведения измерений спектров оптического поглощения (ОП) и фотолюминесценции (ФЛ).
По анализу спектров ОП КТ определены значения энергий оптических переходов. Полосы с наименьшей энергией соответствуют первому экситонному пику поглощения ядра InP. Другие могут быть приписаны оболочке из ZnS. По синему сдвигу осуществлена оценка размера ядер образцов КТ. Для QD-1 исследована температурная зависимость первого экситонного пика поглощения. Спектры ФЛ позволяют предположить, что полосы свечения формируются как экситонными переходами, так и дефектами кристаллической решётки ядра InP.
Синтезирован ряд структур нанопористого оксида алюминия, отожженного при различных температурах, с осаждёнными КТ и исследована их ФЛ. Показано, что после осаждения в AAО НК InP/ZnS, сохраняют свои флуоресцентные свойства, следовательно, можно говорить об успешном создании композитных люминофоров InP/ZnS@AAO. Обсуждаются цветовые характеристики изучаемых образцов. / This study deals with the investigation of optical characteristics of differently sized InP/ZnS colloidal quantum dots (QD-1, QD-2, QD-3) and composite nanostrucrures of anodic aluminum oxide with QDs by means of spectrophotometry and luminescence spectroscopy techniques.
The literature review concerning electronic states in an ideal nanocrystal (NC), synthesis of InP-based QDs, use of NCs for creating nanocomposites and calculating color characteristics of emitters was carried out. The methods of sample preparation and measurements of optical absorption (OA) and photoluminescence (PL) spectra are described.
Values of optical transition energies are determined according to the analysis of QD OA spectra. The bands with the lowest energy correspond to the first exciton absorption peak of the InP core. The other transitions can be attributed to the ZnS shell. The core size of the QD samples was evaluated using the blue shift. The temperature dependence of the first exciton absorption peak was investigated for the QD-1. PL spectra of QDs indicate that the emission bands are formed by exciton transitions and defects of the InP crystal lattice.
A series of structures of nanoporous aluminum oxide, annealed at different temperatures, with deposited QDs were synthesized and their PL were studied. Fluorescent properties of the QDs are found to be retained after the deposition, therefore, InP/ZnS@AAO composite phosphors were successfully created. Сolor characteristics of the samples under study are discussed.
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