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Estabilização de filmes finos de óxido de germânio por incorporação de nitrogênio visando aplicações em nanoeletrônica / Stabilization of germanium oxide films by nitrogen incorporation aiming at applications in nanoelectronicsKaufmann, Ivan Rodrigo January 2013 (has links)
De maneira a melhorar o desempenho de um Transistor de Efeito de Campo Metal-Óxido-Semicondutor (MOSFET), o germânio (Ge) é um forte candidato para substituir o silício (Si) como semicondutor, devido a sua alta mobilidade dos portadores de carga. Contudo, o filme de dióxido de germânio (GeO2) sobre Ge é solúvel em água e suas propriedades elétricas inferiores. Nesse sentido, a proposta desta dissertação de Mestrado é oxinitretar termicamente filmes de GeO2 em atmosfera de óxido nítrico (15NO), de maneira a melhorar as propriedades elétricas e físico-químicas dessas estruturas. Inicialmente, as amostras foram limpas quimicamente usando uma mistura de peróxido de hidrogênio (H2O2) e ácido clorídrico + água (HCl + H2O, 4:1). Os filmes de GeO2 foram crescidos termicamente sobre Ge usando atmosfera de oxigênio enriquecido 97% no isótopo de massa 18 (18O), com parâmetros na qual geraram um filme com espessura de ~5 nm. As oxinitretações foram realizadas em um forno térmico rápido com atmosfera de 15NO, nas temperaturas variando de 400-600°C, nos tempos de 1 a 5 minutos. O objetivo da oxinitretação foi criar um filme de oxinitreto de germânio (GeOxNy) com propriedades físico-químicas satisfatórias para a indústria de microeletrônica. Também foram realizados recozimentos térmicos em atmosfera inerte com objetivo de testar a estabilidade térmicas dos filmes de GeOxNy. Análise com Reação Nuclear (NRA) e Espectrometria de Retroespalhamento Rutherford em geometria de canalização (RBS-c) foram utilizadas para quantificar a quantidade total de oxigênio 18O e 16O, respectivamente. NRP também foi utilizada de modo a determinar o perfil de concentração em função da profundidade para as espécies de 18O e 15N. De modo a investigar a composição química das amostras, Espectroscopia de Fotoelétrons induzidos por raio-X (XPS) foi utilizada. Pelas análises por RBS e NRA do 18O, podemos observar que ocorre troca entre os isótopos de 18O e 16O para todas das temperaturas de oxinitretação. Este resultado corrobora com estudos recentes da literatura. Para as amostras oxinitretadas em 5 minutos a 500°C e todas as amostras oxinitretadas a 550°C e 600°C, ocorre troca isotópica completa. Observamos ainda por NRP que o 15N é incorporado mais superficialmente para as temperaturas de oxinitretação até 550°C. Resultados de XPS indicam formação maior de GeOxNy próximos da superfície das amostras e para temperaturas e/ou tempos maiores. Testes de estabilidade térmica indicam que a incorporação de nitrogênio mais próximo das superfície da amostra inibe a dessorção das espécies de GeO. As amostras que não foram oxinitretadas acabam dessorvendo quase por completo o filme de GeO2 quando realizados os recozimentos térmicos. Este efeito do nitrogênio incorporado próximo da superfície tem grande potencial para uso em camadas interfaciais entre semicondutor e dielétricos de porta. / In order to improve the performance of Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), germanium is a good candidate to replace silicon as semiconductor due to its higher charge carrier mobility. However, the germanium dioxide (GeO2) film over Ge is water soluble and produces poor electrical characteristics. In this way, this Master dissertation proposes thermal oxinitridation of the GeO2 films in nitric oxide (15NO) atmosphere in order to improve its electrical and physico-chemical characteristics. Samples were first cleaned using a mixture of hydrogen peroxide (H2O2) and hydrogen chloride + water (HCl + H2O, 4:1). GeO2 films were thermally grown on Ge using oxygen enriched in 97% in the isotope of mass 18, which generated ~5 nm thick film. Oxinitridation was performed in a rapid thermal furnace under 15NO atmosphere, at the 400-600°C temperature range, and 1-5 minutes time range. The goal was to form a germanium oxinitride film (GeOxNy) with physico-chemical properties that are satisfactory for microelectronics industry. We also performed thermal annealing in inert atmosphere to test the thermal stability of GeOxNy films. Nuclear Reaction Analysis (NRA) and Rutherford Backscattering Spectrometry in channeled geometry (RBS-c) were used to quantify the total amount of oxygen 18O and 16O, respectively. NRP was also performed to determine the 18O and 15N depth distribution. In order to investigate the chemical composition of the samples, X-ray Photoelectron Spectroscopy (XPS) was performed. RBS and NRA analysis showed isotopic exchange between 18O and 16O for all temperatures investigated. This result corroborates previous literature studies. Samples oxynitrided in 5 minutes at 500°C and all the samples oxinitrided at 550-600°C showed complete isotopic exchange. We also observed by NRP that nitrogen incorporation occurs more superficially until 550°C. XPS results indicate more formation of GeOxNy near the surface of the samples and for higher temperatures and/or time of oxinitredation. Thermal stability results indicated that the nitrogen incorporation near the sample surface inhibit the GeO desorption. On the other hand, samples that were not oxynitrided have almost all the GeO2 desorbed when thermal annealing is performed.
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Estabilidade de filmes de GeOxNy crescidos termicamente sobre GeCopetti, Gabriela January 2015 (has links)
A instabilidade térmica do óxido de germânio (GeO2) é um obstáculo à utilização de germânio (Ge) como material semicondutor em dispositivos MOSFET. Essa instabilidade é induzida por vacâncias de oxigênio originadas de uma reação interfacial entre o óxido e o substrato. Essas vacâncias são responsáveis pela dessorção de GeO da superfície do óxido e pela deterioração das propriedades elétricas do transistor. Estudos sugerem que a incorporação de nitrogênio no GeO2 aumenta a sua estabilidade. Nesta dissertação, filmes de oxinitreto de germânio (GeOxNy) foram crescidos termicamente sobre Ge, utilizando gás óxido nítrico (NO), em um forno aquecido resistivamente. Técnicas de análise por feixe de íons, como espectrometria de retroespalhamento Rutherford e análise por reações nucleares, foram utilizadas para investigar o transporte atômico durante o crescimento dos filmes e o papel do nitrogênio na estabilização do óxido. Para a determinação da espessura, da densidade e da rugosidade de alguns filmes, foram realizadas medidas de reflectometria de raios X. Os resultados mostram que a incorporação de uma pequena quantidade de nitrogênio resulta em uma diminuição substancial na dessorção de GeO e na formação de uma barreira eficiente contra a oxidação adicional do substrato. Átomos de nitrogênio incorporados na estrutura do óxido podem reduzir a difusividade das vacâncias de oxigênio, levando ao aumento da estabilidade térmica. / The thermal instability of germanium oxide (GeO2) hinders the use of germanium (Ge) as the semiconductor material in MOSFET devices. This instability is induced by oxygen vacancies originated from the interfacial reaction between the oxide and the substrate. These vacancies are responsible for GeO desorption from the oxide surface and deterioration of the device’s eletrical properties. Previous studies suggest that nitrogen incorporation increases the oxide’s stability. In this dissertation, germanium oxynitride (GeOxNy) films were thermally grown on Ge using nitric oxide (NO) gas, in a conventional resistively heated furnace. Ion beam analysis tecniques, such as Rutherford backscattering spectrometry and nuclear reaction analysis, were used to investigate atomic transport during thermal growth and the role of nitrogen in the improved stability. Film thickness, density and roughness were obtained through X-ray reflectometry. Results show that the incorporation of a small amount of nitrogen yields a substantial decrease in GeO desorption and the formation of a strong barrier against further oxidation of the substrate. Nitrogen atoms incorporated into the oxide structure may decrease oxygen vacancy diffusivity, leading to enhanced thermal stability.
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Estabilização de filmes finos de óxido de germânio por incorporação de nitrogênio visando aplicações em nanoeletrônica / Stabilization of germanium oxide films by nitrogen incorporation aiming at applications in nanoelectronicsKaufmann, Ivan Rodrigo January 2013 (has links)
De maneira a melhorar o desempenho de um Transistor de Efeito de Campo Metal-Óxido-Semicondutor (MOSFET), o germânio (Ge) é um forte candidato para substituir o silício (Si) como semicondutor, devido a sua alta mobilidade dos portadores de carga. Contudo, o filme de dióxido de germânio (GeO2) sobre Ge é solúvel em água e suas propriedades elétricas inferiores. Nesse sentido, a proposta desta dissertação de Mestrado é oxinitretar termicamente filmes de GeO2 em atmosfera de óxido nítrico (15NO), de maneira a melhorar as propriedades elétricas e físico-químicas dessas estruturas. Inicialmente, as amostras foram limpas quimicamente usando uma mistura de peróxido de hidrogênio (H2O2) e ácido clorídrico + água (HCl + H2O, 4:1). Os filmes de GeO2 foram crescidos termicamente sobre Ge usando atmosfera de oxigênio enriquecido 97% no isótopo de massa 18 (18O), com parâmetros na qual geraram um filme com espessura de ~5 nm. As oxinitretações foram realizadas em um forno térmico rápido com atmosfera de 15NO, nas temperaturas variando de 400-600°C, nos tempos de 1 a 5 minutos. O objetivo da oxinitretação foi criar um filme de oxinitreto de germânio (GeOxNy) com propriedades físico-químicas satisfatórias para a indústria de microeletrônica. Também foram realizados recozimentos térmicos em atmosfera inerte com objetivo de testar a estabilidade térmicas dos filmes de GeOxNy. Análise com Reação Nuclear (NRA) e Espectrometria de Retroespalhamento Rutherford em geometria de canalização (RBS-c) foram utilizadas para quantificar a quantidade total de oxigênio 18O e 16O, respectivamente. NRP também foi utilizada de modo a determinar o perfil de concentração em função da profundidade para as espécies de 18O e 15N. De modo a investigar a composição química das amostras, Espectroscopia de Fotoelétrons induzidos por raio-X (XPS) foi utilizada. Pelas análises por RBS e NRA do 18O, podemos observar que ocorre troca entre os isótopos de 18O e 16O para todas das temperaturas de oxinitretação. Este resultado corrobora com estudos recentes da literatura. Para as amostras oxinitretadas em 5 minutos a 500°C e todas as amostras oxinitretadas a 550°C e 600°C, ocorre troca isotópica completa. Observamos ainda por NRP que o 15N é incorporado mais superficialmente para as temperaturas de oxinitretação até 550°C. Resultados de XPS indicam formação maior de GeOxNy próximos da superfície das amostras e para temperaturas e/ou tempos maiores. Testes de estabilidade térmica indicam que a incorporação de nitrogênio mais próximo das superfície da amostra inibe a dessorção das espécies de GeO. As amostras que não foram oxinitretadas acabam dessorvendo quase por completo o filme de GeO2 quando realizados os recozimentos térmicos. Este efeito do nitrogênio incorporado próximo da superfície tem grande potencial para uso em camadas interfaciais entre semicondutor e dielétricos de porta. / In order to improve the performance of Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), germanium is a good candidate to replace silicon as semiconductor due to its higher charge carrier mobility. However, the germanium dioxide (GeO2) film over Ge is water soluble and produces poor electrical characteristics. In this way, this Master dissertation proposes thermal oxinitridation of the GeO2 films in nitric oxide (15NO) atmosphere in order to improve its electrical and physico-chemical characteristics. Samples were first cleaned using a mixture of hydrogen peroxide (H2O2) and hydrogen chloride + water (HCl + H2O, 4:1). GeO2 films were thermally grown on Ge using oxygen enriched in 97% in the isotope of mass 18, which generated ~5 nm thick film. Oxinitridation was performed in a rapid thermal furnace under 15NO atmosphere, at the 400-600°C temperature range, and 1-5 minutes time range. The goal was to form a germanium oxinitride film (GeOxNy) with physico-chemical properties that are satisfactory for microelectronics industry. We also performed thermal annealing in inert atmosphere to test the thermal stability of GeOxNy films. Nuclear Reaction Analysis (NRA) and Rutherford Backscattering Spectrometry in channeled geometry (RBS-c) were used to quantify the total amount of oxygen 18O and 16O, respectively. NRP was also performed to determine the 18O and 15N depth distribution. In order to investigate the chemical composition of the samples, X-ray Photoelectron Spectroscopy (XPS) was performed. RBS and NRA analysis showed isotopic exchange between 18O and 16O for all temperatures investigated. This result corroborates previous literature studies. Samples oxynitrided in 5 minutes at 500°C and all the samples oxinitrided at 550-600°C showed complete isotopic exchange. We also observed by NRP that nitrogen incorporation occurs more superficially until 550°C. XPS results indicate more formation of GeOxNy near the surface of the samples and for higher temperatures and/or time of oxinitredation. Thermal stability results indicated that the nitrogen incorporation near the sample surface inhibit the GeO desorption. On the other hand, samples that were not oxynitrided have almost all the GeO2 desorbed when thermal annealing is performed.
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Material migration in tokamaks : Erosion-deposition patterns and transport processesWeckmann, Armin January 2017 (has links)
Controlled thermonuclear fusion may become an attractive future electrical power source. The most promising of all fusion machine concepts is called a tokamak. The fuel, a plasma made of deuterium and tritium, must be confined to enable the fusion process. It is also necessary to protect the wall of tokamaks from erosion by the hot plasma. To increase wall lifetime, the high-Z metal tungsten is foreseen as wall material in future fusion devices due to its very high melting point. This thesis focuses on the following consequences of plasma impact on a high-Z wall: (i) erosion, transport and deposition of high-Z wall materials; (ii) fuel retention in tokamak walls; (iii) long term effects of plasma impact on structural machine parts; (iv) dust production in tokamaks. An extensive study of wall components has been conducted with ion beam analysis after the final shutdown of the TEXTOR tokamak. This unique possibility offered by the shutdown combined with a tracer experiment led to the largest study of high-Z metal migration and fuel retention ever conducted. The most important results are: - transport is greatly affected by drifts and flows in the plasma edge; - stepwise transport along wall surfaces takes place mainly in the toroidal direction; - fuel retention is highest on slightly retracted wall elements; - fuel retention is highly inhomogeneous. A broad study on structural parts of a tokamak has been conducted on the TEXTOR liner. The plasma impact does neither degrade mechanical properties nor lead to fuel diffusion into the bulk after 26 years of duty time. Peeling deposition layers on the liner retain fuel in the order of 1g and represent a dust source. Only small amounts of dust are found in TEXTOR with overall low deuterium content. Security risks in future fusion devices due to dust explosions or fuel retention in dust are hence of lesser concern. / <p>QC 20170630</p>
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Wachstum epitaktischer CoSi$_2$-Schichten durch Reaktion metallischer Doppelschichten mit Si(100)Gebhardt, Barbara 04 November 1999 (has links)
Die Bildung von CoSi$_2$-Schichten mittels TIME-Verfahren (TIME: Ti-Interlayer Mediated Epitaxy) wurde untersucht. Dabei wurde die Ti-Zwischenschicht durch eine Hf-Zwischenschicht ersetzt. Der Einfluss der Prozessparameter (Tempertemperatur, Temperzeit, Aufheizrate und Ausgangsschichtdicken) und des Metalls (Hf, Ti, Zr) der Zwischenschicht auf die Reaktion der metallischen Doppelschichten mit Si(100) wurde ermittelt. Zur Charakterisierung der Proben wurden RBS-, TEM-, XRD- und AES-Untersuchungen durchgefuehrt. Die Ausbildung eines Mehrschichtsystems nach der Temperung der Doppelschichten in Abhaengigkeit der Prozessparameter wird dargestellt. Es wird gezeigt, dass die Prozessparameter die Temperatur bestimmen, bei der die CoSi$_2$-Keimbildung stattfindet. Anhand dieser Untersuchungen wird nachgewiesen, dass sich mit Erhoehung der CoSi$_2$-Keimbildungstemperatur die epitaktische Qualitaet der gebildeten CoSi$_2$-Schicht verbessert. Die Erklaerung des Reaktionsablaufs der metallischen Doppelschichten mit Si(100) erfolgt anhand eines aufgestellten Reaktionsschemas. Zur Entfernung der Deckschicht wurden verschiedene Aetzverfahren angewandt und deren Wirkung verglichen. / The formation of a CoSi$_2$ layer by solid phase reaction of metallic bilayer with Si (TIME: Ti-Interlayer Mediated Epitaxy) was investigated. In this work the Ti was replaced by Hf. The influence of the annealing temperature, the annealing time, the heating rate and the thicknesses of the metallic layers on the reaction of the bilayer with Si was determined. The samples were characterised by Rutherford-backscattering (RBS), Transmission-Electron-Microscopy (TEM), X-ray-Diffraction and Auger-Electron-Spectroscopy (AES) studies. During the annealing of the samples a system of layers is formed. It was shown, that the annealing parameters and the thicknesses of the layer determine the temperature, on which the nucleation of CoSi$_2$ occurs. A decrease of this nucleation temperature leads to an improvement of the quality of the epitaxial CoSi$_2$ layer. A model of reaction is presented, which explains the reaction of the metallic bilayer with Si. The removal of the top layer by several etching procedures was investigated and the results were compared.
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Untersuchungen zum Wachstum dünner NiSi(2-x)Al(x)- und NiSi(2-x)Ga(x)-Schichten auf Si(001)Allenstein, Frank 12 January 2007 (has links)
Im Rahmen dieser Arbeit wurden erste Untersuchungen zur Herstellung dünner NiSi(2-x)Al(x)- bzw. NiSi(2-x)Ga(x)-Schichten auf Si(001) erbracht.
Dazu wurden Ni-Si-Al-Schichten mittels DC-Magnetron-Sputtern sowie Ni-Si-Ga-Schichten mittels Molekular-Strahl-Epitaxie (MBE) abgeschieden und anschließend in Abhängigkeit von der Herstellungsprozedur in einer RTA-Anlage thermisch behandelt.
Die so entstandenen Reaktionsschichten wurden anschließend mittels RBS charakterisiert, wobei zusätzlich REM-, TEM-, AES-Tiefenprofil- und XRD-Untersuchungen ergänzend genutzt wurden.
Es zeigt sich, dass unabhängig von der Abscheideprozedur bei ausreichend hoher Temper- bzw. Substrattemperatur die thermodynamisch stabilen Endphasen NiSi(2-x)Al(x) bzw. NiSi(2-x)Ga(x) gebildet werden.
Während die Bildungstemperatur bei Festphasenreaktionen ohne Al- bzw. Ga-Zugabe für NiSi2 etwa 700°C beträgt, reduziert sich diese unter Anwesenheit von Al- bzw. Ga-Atomen auf 500°C und darunter.
Dabei scheinen bereits eine Al- bzw. Ga-Konzentration von unter einem Atomprozent als notwendiger Stoffmengenanteil auszureichen.
Befindet sich der Ort der Keimbildung der NiSi(2-x)Al(x)- bzw. NiSi(2-x)Ga(x)-Kristallite an der Grenzfläche zum Si(001)-Substrat, so ist eine Änderung der bevorzugten Wachstumsorientierung von NiSi(2-x)Al(x)(001)[100] || Si(001)[100] bzw. NiSi(2-x)Ga(x)(001)[100] || Si(001)[100] (A-Typ) zu einer NiSi(2-x)Al(x)(220) || Si(001)- bzw. NiSi(2-x)Ga(x)(220) || Si(001)-Vorzugsorientierung festzustellen.
Die dafür notwendige Konzentration von Al- bzw. Ga-Atomen scheint jedoch höher zu sein als die, die für die Erniedrigung der Bildungstemperatur notwendig ist.
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Politics and Parochial Schools in Archbishop John Purcell's OhioGutowski, James Arthur 29 September 2009 (has links)
No description available.
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Development of Tantalum-Doped Tin Oxide as New Solar Selective Material for Solar Thermal Power PlantsLungwitz, Frank 15 April 2024 (has links)
Solar absorber coatings are one of the key components in concentrated solar power (CSP) plants. Currently operating at temperatures up to 565°C and suffering from emissive losses, their energy conversion efficiency could be improved by applying high-temperature stable materials with solar selective properties, i.e. high absorptivity and low emissivity. In this work, the transparent conductive oxide (TCO) SnO2:Ta is developed as a solar selective coating (SSC) for CSP absorbers. Starting with simulations covering basic requirements for SSCs, the deposition process of SnO2:Ta is optimized and extensive optical characterization and modelling are performed. It is shown that upon covering with a SiO2 antireflective layer, a calculated absorptivity of 95% and an emissivity of 30% are achieved for the model configuration of SnO2:Ta on top of a perfect black body (BB). High-temperature stability of the developed TCO up to 800 °C is shown in situ by spectroscopic ellipsometry and Rutherford backscattering spectrometry. The universality of the concept is then demonstrated by transforming silicon and glassy carbon from non-selective into solar selective absorbers by depositing the TCO on top of them. Finally, the energy conversion efficiencies ηCSP of SnO2:Ta on top of a BB and an ideal non-selective BB absorber are compared as a function of solar concentration factor C and absorber temperature TH.
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Evaluation of amorphous oxide semiconductors for thin film transistors (TFTs) and resistive random access memory (RRAM) applicationsRajachidambaram, Jaana Saranya 06 January 2013 (has links)
Thin-film transistors (TFTs) are primarily used as a switching element in liquid crystal
displays. Currently, amorphous silicon is the dominant TFT technology for displays, but
higher performance TFTs will become necessary to enable ultra-definition resolution
high-frequency large-area displays. Amorphous zinc tin oxide (ZTO) TFTs were
fabricated by RF magnetron sputter deposition. In this study, the effect of both deposition
and post annealing conditions have been evaluated in regards to film structure,
composition, surface contamination, and device performance. Both the variation of
oxygen partial pressure during deposition and the temperature of the post-deposition
annealing were found to have a significant impact on TFT properties. X-ray diffraction
data indicated that the ZTO films remain amorphous even after annealing to 600° C.
Rutherford backscattering spectrometry indicated that the Zn:Sn ratio of the films was
~1.7:1 which is slightly tin rich compared to the sputter target composition. X-ray
photoelectron spectroscopy data indicated that the films had significant surface
contamination and that the Zn:Sn ratios changed depending on sample annealing
conditions. Electrical characterization of ZTO films using TFT test structures indicated
that mobilities as high as 17 cm² V⁻¹ s⁻¹ could be obtained for depletion mode devices. It
was determined that the electrical properties of ZTO films can be precisely controlled by
varying the deposition conditions and annealing temperature. It was found that the ZTO
electrical properties could be controlled where insulating, semiconducting and conducting
films could be prepared. This precise control of electrical properties allowed us to
incorporate sputter deposited ZTO films into resistive random access memory (RRAM)
devices. RRAM are two terminal nonvolatile data memory devices that are very
promising for the replacement of silicon-based Flash. These devices exhibited resistive
switching between high-resistance states to low-resistance states and low-resistance states
to high-resistance states depending on polarity of applied voltages and current
compliance settings. The device switching was fundamentally related to the defect states
and material properties of metal and insulator layers, and their interfaces in the metalinsulator-metal (MIM) structure. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Jan. 6, 2012 - Jan. 6, 2013
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In Situ and Ex Situ Investigations of Transition Metal-Catalyzed Crystallization of Carbon and Silicon Thin FilmsWenisch, Robert 29 October 2018 (has links)
Transition metal interface effects of on the crystallization of carbon and silicon were investigated. The graphitization of carbon was studied by ion beam sputter deposition of atomic carbon onto a nickel surface at temperatures ranging from room temperature to 550 °C. The resulting films were characterized by X-ray photoelectron spectroscopy, nuclear reaction analysis combined with Rutherford backscattering spectrometry, Raman spectroscopy and transmission electron microscopy. A temperature-induced and a nickel-induced effect on the graphitic ordering is demonstrated. The carbon films showed a two layered structure: directly on the nickel surface up to 8 monolayers of graphitic carbon, further deposited carbon formed less ordered structures, preferably perpendicular to the surface. The results are discussed on the basis of hyperthermal atom deposition, surface diffusion, metal-induced crystallization and dissolution-precipitation. The analysis points to a dominating role of surface diffusion-assisted crystallization in the carbon ordering process.
The kinetics of silver-induced crystallization of amorphous silicon were studied in a series of isothermal annealing experiments at 350 °C, 400 °C, 450 °C and 500 °C. The annealing process was monitored in situ employing Raman spectroscopy and Rutherford backscattering spectrometry from which time resolved information on the phase transformation and hence the kinetics are obtained. The grain structure of the crystallized silicon film was investigated with optical and scanning electron microscopy which reveals grain diameters of 5 to 8 µm. The small scale crystallinity was measured with X-ray diffraction and crystal domain sizes from 20 to 50 nm were observed. The phase transformation kinetics are discussed based on the Johnson-Mehl-Avrami-Kolmogorov theory. The analysis points to a two-dimensional, diffusion limited process with fast Avrami-type nucleation and an activation energy of 0.8 eV/at.:Contents
1. Introduction
2. Metal-Induced Crystallization
2.1. Introduction and State of the Art of Metal-Induced Crystalliza-tion
2.2. Thermodynamics of Metal-Induced Crystallization
2.3. Kinetics of Metal-Induced Crystallization
3. Ion Beam Analysis
3.1. Rutherford Backscattering Spectrometry
3.2. Nuclear Reaction Analysis
4. Raman Spectroscopy
4.1. Light Scattering in Solids
4.2. Theory
4.2.1. The Raman Spectrum of Graphitic Carbon
4.2.2. The Silicon Raman Spectrum
5. The Cluster Tool at the Ion Beam Center
5.1. General Concept
5.2. Sputtering Chamber
5.3. The Environmental Chamber
5.4. The Analysis Chamber
5.5. The Ion Beam Analysis Chamber
5.5.1. The Experimental Setup
6. The Carbon Nickel System
6.1. Experimental Details
6.1.1. Film growth
6.1.2. Characterization
6.2. Results
6.3. Discussion
7. The Silicon Silver System
7.1. Experimental
7.1.1. Film Preparation
7.1.2. In Situ Raman Spectroscopy
7.1.3. In Situ Rutherford Backscattering Spectrometry
7.2. Results
7.2.1. Raman Spectroscopy
7.2.2. Rutherford Backscattering Spectrometry
7.2.3. X-ray Diffraction
7.2.4. Optical and Scanning Electron Microscopy
7.3. Discussion
8. Conclusion and Outlook
A. Appendix
A.1. Spectroscopic Lineshapes
A.1.1. The Lorentzian Lineshape
A.1.2. The Breit-Wigner-Fano Lineshape
A.1.3. The Doniach-Sunjic Lineshape
A.1.4. The Gaussian Lineshape
A.1.5. The Voigt Lineshape
A.2. Statistcial Distribution Functions
A.2.1. The Gamma Distribution
Bibliography / Der Einfluss von Übergangsmetallkontaktflächen auf die Kristallisation von Kohlenstoff und Silizium wurde untersucht. Dazu wurde Kohlenstoff bei Temperaturen von Raumtemperatur bis 550 °C auf Nickel mittels Ionenstrahl-Sputtern abgeschieden. Die so erzeugten Filme wurden mit Röntgenphotoelektronen Spektroskopie, Kernreaktionsanalyse kombiniert mit Rutherford Rückstreu Spektrometrie, Raman Spektroskopie und Transmissions-Elektronenmikroskopie charakterisiert. Ein Nickel- und ein Temperatureffekt auf den Graphitisierungsprozess wird nachgewiesen. Die Kohlenstofffilme zeigten einen zweilagigen Aufbau: Direkt auf der Nickeloberfläche bis zu 8 Monolagen graphitischen Kohlenstoffs, weiterer abgeschiedener Kohlenstoff bildet weniger geordnete Strukturen, die bevorzugt senkrecht zur Oberfläche ausgerichtet sind. Die Ergebnisse werden auf Basis von hyperthermischer, atomarer Abscheidung, Oberflächendiffusion, Metall-induzierte Kristallisation und Lösung-Ausfällung diskutiert. Die Analysen deuten auf eine dominante Rolle der Oberflächendiffusion im Graphitisierungsprozess hin.
Die Kinetik der Silber-induzierten Kristallisation von amorphen Silizium wurde in einer Reihe von isothermalen Temperexperimenten bei 350 °C, 400 °C, 450 °C und 500 °C untersucht. Der Tempervorgang wurde mit in situ Raman Spektroskopie und in situ Rutherford Rückstreu Spektrometrie charakterisiert, wodurch zeitaufgelöste Information über den Phasenübergang und damit die Kinetik gewonnen wurden. Das Gefüge der entstandenen Siliziumschichten wurde mit optischer und Rasterelektronenmikroskopie untersucht, welche Korndurchmesser von 5 bis 8 µm zeigten. Die Kristallinität wurde mit Röntgendiffraktometrie analysiert. Hierdurch wurden Kristallitgrößen von 20 bis 50 nm bestimmt. Die Kinetik des Phasenüberganges wird anhand der Johnson-Mehl-Avrami-Kolmogorov Theorie diskutiert. Dies deutet auf einen zeidimensionalen, diffusionslimitierten Prozess mit schnell abklingender Avrami-Keimbildung hin. Die Aktivierungsenergie wurde zu 0.8 eV/At. bestimmt.:Contents
1. Introduction
2. Metal-Induced Crystallization
2.1. Introduction and State of the Art of Metal-Induced Crystalliza-tion
2.2. Thermodynamics of Metal-Induced Crystallization
2.3. Kinetics of Metal-Induced Crystallization
3. Ion Beam Analysis
3.1. Rutherford Backscattering Spectrometry
3.2. Nuclear Reaction Analysis
4. Raman Spectroscopy
4.1. Light Scattering in Solids
4.2. Theory
4.2.1. The Raman Spectrum of Graphitic Carbon
4.2.2. The Silicon Raman Spectrum
5. The Cluster Tool at the Ion Beam Center
5.1. General Concept
5.2. Sputtering Chamber
5.3. The Environmental Chamber
5.4. The Analysis Chamber
5.5. The Ion Beam Analysis Chamber
5.5.1. The Experimental Setup
6. The Carbon Nickel System
6.1. Experimental Details
6.1.1. Film growth
6.1.2. Characterization
6.2. Results
6.3. Discussion
7. The Silicon Silver System
7.1. Experimental
7.1.1. Film Preparation
7.1.2. In Situ Raman Spectroscopy
7.1.3. In Situ Rutherford Backscattering Spectrometry
7.2. Results
7.2.1. Raman Spectroscopy
7.2.2. Rutherford Backscattering Spectrometry
7.2.3. X-ray Diffraction
7.2.4. Optical and Scanning Electron Microscopy
7.3. Discussion
8. Conclusion and Outlook
A. Appendix
A.1. Spectroscopic Lineshapes
A.1.1. The Lorentzian Lineshape
A.1.2. The Breit-Wigner-Fano Lineshape
A.1.3. The Doniach-Sunjic Lineshape
A.1.4. The Gaussian Lineshape
A.1.5. The Voigt Lineshape
A.2. Statistcial Distribution Functions
A.2.1. The Gamma Distribution
Bibliography
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