The exploitation of the soft x-ray/extreme ultra-violet (EUV) region of the electromagnetic spectrum is possible mainly due to the development of multilayer (ML) mirrors. This region of the electromagnetic spectrum offers great opportunities in both science and technology. The shorter wavelength allows one to see smaller features in microscopy and write finer features in lithography. High reflectivity with moderate spectral bandwidth at normal/near-normal incidence can be achieved in soft x-ray/ EUV spectral range using these ML mirrors, where natural crystals with the required large periodicity are not available. These MLs are generally artificial Bragg’s reflectors, which consist of alternative high and low density materials with periodicity in the nanometer range. The main advantages of ML optics stem from the tunability of layer thickness, composition, lateral gradient, and the gradient along the normal to the substrate; these can be tailored according to the desired wavelength regime. They have the great advantage of being adaptable to figured surfaces, enabling their use as reflective optics in these spectral regions, for focusing and imaging applications. Broadband reflectivity and wavelength tunability are also possible by using MLs with normal and lateral gradient, respectively. However, fabrication of these ML mirrors requires the capability to deposit uniform, ultra-thin (a few angstroms-thick) films of different materials with thickness control on the atomic scale. Thus, one requires a proper understanding of substrate surfaces, individual layers, chemical reactivity at interfaces and, finally, of the ML structures required for particular applications. The performance of these MLs is limited by (the lack of) contrast in optical constants of the two materials, interfacial roughness, the chemical reactivity of two materials and, finally, errors in the thickness of individual layers. Soft x-ray/extreme ultra-violet ML mirrors have found a wide range of applications in synchrotron radiation beam lines, materials science, astronomy, x-ray microscopy, x-ray laser, x-ray lithography, polarizers, and plasma diagnostics. The Indus–1 synchrotron radiation (SR) source is an operational 450 MeV machine, which produces radiation up to soft x-rays. Indus-2 is a 2.5 GeV machine, which has been commissioned recently to produce hard x-rays (E > 25 keV). The combination of Indus-1 and Indus-2 will cover a broad energy spectrum from IR to hard x-rays. Therefore, there is a significant need and opportunity to study MLs of different pairs of materials, with different parameters such as periodicity and optimum thickness of individual layers. The goal of the present thesis is to fabricate MLs for soft x-ray optics and to study their physics for application as polarizers in the wavelength range from 67 Å to 160 Å on the Indus-1 synchrotron source. To accomplish this task, a UHV electron beam evaporation system has been developed indigenously for the fabrication of MLs. Three different ML systems viz., Mo/Si, Fe/B4C and Mo/Y have been fabricated, and their surfaces and interfaces were investigated thoroughly for the polarizer application. X-ray reflectivity (XRR) has been used extensively in the investigations of these MLs. This is because XRR is a highly sensitive non-destructive technique for the characterization of buried interfaces, and gives microscopic information (at atomic resolution) over a macroscopic length scale (a few microns). Numerical analysis of XRR data has been carried out using computer programs. Depth-graded x-ray photoelectron spectroscopy (XPS) has been used for compositional analysis at interfaces for some of the ML structures, as a technique complementary to XRR. The performance of some of these MLs has been tested in the soft x-ray region, using the Indus-1 synchrotron radiation (SR) source. Prior to studying the MLs, a detailed study of the surfaces and interfaces of thin films, bi-layers, and tri-layers was carried out using XRR and the glancing incidence fluorescence technique. The discontinuous-to-continuous transition and the mode of film growth, which are vital to the optimization of layer thickness (basically for the high-atomic number or high-Z layer) in the ML structures, were also investigated using in situ sheet resistance measurement method. Indus-1 is a soft x-ray SR source that covers atomic absorption edges of many low-Z materials. The present work demonstrates the possibilities of characterizing low-Z thin films and multilayers using soft x-ray resonant reflectivity. In one case, we have shown for first time that soft x-ray resonant reflectivity can be employed as a non-destructive technique for the determination of interlayer composition. In a second study using the Indus-1 SR source, we have shown, by observing the effect of the anomalous optical constant on reflectivity pattern when photon energy is tuned across the atomic absorption edge of the constituent low-Z element, that soft x-ray resonant reflectivity is an element-specific technique. This thesis is organized into 7 chapters. A brief summary of individual chapters is presented below. Chapter 1 gives a brief general introduction to x-ray ML optics. This is followed by a discussion of the importance of the soft x-ray region of electromagnetic radiation. The optical properties of x-rays are reviewed and optical constants are calculated for some of the important materials used for x-ray MLs. The refractive index in the x-ray region being less than unity (except absorption edges), the consequent limitation of conventional transmission lenses is discussed. The limitation of glancing angle incidence optics is presented, motivating the need for ML optics, which is discussed along with a theoretically calculated reflectivity profile. The procedure for materials for the MLs for application in different spectral regions is discussed, along with a survey of literature related to the present thesis. The importance of the quality of surfaces and interfaces on the performance of ML structures has been shown through simulations. The applications of soft x-ray MLs are discussed with emphasis on polarization. This is followed by a review of different modes of growth of thin films. Finally, the scope of the present work is highlighted. Chapter 2 provides brief descriptions of the experimental techniques used in the present investigations and of the numerical methods employed for quantitative data analysis. The XRR technique is discussed elaborately because it has been used extensively. Detailed calculations of x-ray reflectivity from single surfaces, thin films and bi-layers are presented, along with simulated values. The effect of critical angle and Brewster’s angle is also discussed. Data analysis methods for computing x-ray reflectivity from multilayer structures, based on dynamical and kinematical models, have been discussed. The effect of roughness on XRR has been discussed based on the recursion formalism of dynamical theory. Simulations of XRR and experimental XRR data fitting are carried out using computer programs. The XRR experimental set up is also outlined. A theoretical background is given for the electrical measurements on thin films. This is followed by a brief overview of x-ray photoelectron spectroscopy (XPS) and interpretation of spectra. Finally, the glancing incidence x-ray fluorescence (GIXRF) technique is outlined. Chapter 3 describes in detail the ultra-high vacuum electron beam evaporation system developed in house especially for the fabrication of thin films and x-ray multilayer optics. At the outset, a brief overview of different deposition techniques commonly used for the fabrication of x-ray optical elements is presented. Design, fabrication, and assembly of different accessories are discussed. The control of thickness and uniformity of the films deposited has been checked through the experiments, whose results are provided. The results obtained for ML test structures are presented to show the capability of system in carrying out fabrication of high quality x-ray ML structures. Finally, the versatility of evaporation system incorporating in situ characterization facilities such as -situ electrical measurements for different substrate temperatures is illustrated. Chapter 4 presents a study of the growth of ultra-thin Mo films at different substrate temperatures using in situ sheet resistance measurements. First, a theoretical background is given on the different stages of island growth and on factors affecting thin film growth, followed by a discussion of the possible electrical conduction phenomena in continuous and discontinuous metal films. The nature of thin film growth and a detailed microscopic picture at different growth stages are derived from a modeling of sheet resistance data obtained in situ. The various conduction mechanisms have been identified in different stages of growth. In the island growth stage, the isotropic and anisotropic growth of Mo islands is identified from the model. In the insulator-metal transition region, experimentally determined values of critical exponent of conductivity agrees well with theoretically predicted values for a two-dimensional (2D) percolating system, revealing that Mo films on float glass substrate is predominantly a 2D structure. The minimum thickness for which Mo films becomes continuous is obtained as 1.8 nm and 2.2 nm for Mo deposited at substrate temperatures 300 K and 100 K, respectively. An amorphous-to- crystalline transition is also observed, and discussed. Chapter 5 covers the detailed study of the surfaces and interfaces studies in three different ML structures viz., Mo/Si, Fe/B4C and Mo/Y, meant for the polarizer application in the wavelength range of 67 Å to 160 Å. Multilayers with varying periodicity, varying number of layer pairs, and different ratios of high-Z layer thickness to the period, were fabricated using the electron beam system. Initially, a brief overview of the design aspects of ML structures is given, along with the theoretically calculated reflectivity at Brewster’s angle from the best material combinations. In Mo/Si MLs, the interlayer formed at the interfaces due to interdiffusion of the two elements is asymmetric in thickness, i.e., Mo-on-Si interlayer is thicker than the Si-on-Mo interlayer. To take account of these interlayers in XRR data fitting, a four layer model is considered. The effect of interlayers on reflectivity pattern was studied using simulations, and differences with respect to roughness are also discussed. The mechanism of formation of asymmetric interlayers is also discussed. The interlayer composition has determined using depth-graded XPS. The results reveal the formation of the MoSi2 composition at both the interfaces. The experimental results agree well with theoretical calculations based on solid-state amorphization reaction, which is a result of large heat of mixing. The effective heat of formation model reveals the formation of MoSi2 as the first phase. The soft x-ray reflectivity performance of the Mo/Si ML structure at Brewster’s angle is tested using Indus-1 synchrotron radiation (SR). Using XRR and GIXFR, a study of the surfaces and interfaces of bilayers of B4C-on-Fe and Fe-on- B4C, and tri-layers of Fe-B4C-Fe was carried out, with a systematic variation of Fe and B4C layer thicknesses. A sharp interface was observed in Fe-on-B4C, whereas a low density (w.r.t. Fe) interlayer is observed at the B4C-on-Fe interface. The interlayer properties fluctuates w.r.t. the bottom Fe layer thickness and is independent of the top B4C layer thickness. The nature of fluctuations has been discussed in detail. A study of the surfaces and interfaces of Fe/B4C MLs is described. Finally, a study of the surfaces and interfaces of bilayers, tri-layers, and MLs of the Mo/Y system is discussed in detail. Chapter 6 describes the application of soft x-ray resonant reflectivity for the characterization of low-Z thin films and interfaces in multilayer structures. Initially, a discussion of the energy dependence of atomic scattering factors and hence of optical constants is provided with simulations, with emphasis on the atomic absorption edge. Then, a brief overview of synchrotron radiation, with particular emphasis on the parameters of the Indus-1 synchrotron source is given. The possibilities of determining the composition of the buried interlayer with sub-nanometer scale sensitivity using soft x-ray resonant reflectivity are discussed. The methodology has been applied to study the Mo/Si interface both by simulations and by experiments on the Indus-1 SR, by tuning the photon energy to the Si L-absorption edge. Finally, direct evidence of elemental specificity of soft x-ray resonant reflectivity through the observation of the effect of anomalous optical constants on the reflectivity pattern is discussed. We demonstrate the method through simulations and experiments on the B4C material in B4C thin films and Fe/ B4C bi-layers, using Indus-1 SR tuned to the boron Kedge. Chapter 7 summarizes the main findings of the present work, and provides an outlook for further investigations in the field.

Polypropylene (PP) is a common thermoplastic and frequently adapted permanently with increasing requirements by adding fillers as well as reinforcing materials. Because of incompatibility of non-polar PP and polar inorganic filler, resulting composites are brittle which has a detrimental effect on the desired properties. Improvements in mechanical properties can be reached by compatibilization, creating of chemical couplings between phases and by increasing of inhomogeneity. Thus, maleic anhydride grafted PP is used as well as reactive processing of PP in presence of peroxide radical initiators. The temperature dependence of peroxide decay as well as the dependence of radical generation rate on time are two disadvantages of peroxide induced reactive processing. Modification of polymers with high energy electron treatment is also well known and used to form parts (after) molding as well as raw materials (pellets, powders, fibers) in solid state and at room temperature. The spatially and temporally precise input of energy is used to produce desired material properties on radical-induced chemical reactions. Coupling of high energy electron modification of polymers and melt mixing offers a new possibility of reactive processing. In this case, radical generation is independent of temperature, can be easily controlled by beam current and kept constant over time. Absence of any crystallinity, high reaction rates as well as intensive macromolecular mobility and intensive mixing are reasons to expect novel structures and properties. Electron beam induced reactive processing is a novel technique where chemical reactions are induced by spatial and temporal precise energy input via high energy electrons under dynamic conditions of melt mixing. This method gives the possibility to increase surface energy of polypropylene (PP) effectively as well as to generate chemical couplings between filler and PP. The process was applied to a proved system consisting of PP (38 wt%), magnesium hydroxide (MH) (60 wt%), triallyl cyanurate (TAC) (2 wt%). This composite system was successful tested in peroxide induced conventional reactive processing. Absorbed dose imparted per rotation of rotors is a new parameter controlling mechanical properties of polymer composites. Improved properties were found in tensile strength (150 %), elongation at break (175 %), and impact strength (175 %). It can be shown that chemical couplings are generated during electron induced reactive processing in comparison to only compatibilized material.

No description available.

The present dissertation reports the findings of a study of cracking behavior of a newly developed superalloy, Allvac 718Plus during high power beam welding and post-weld heat treatment. Microstructures of the base alloy, heat affected zone (HAZ) and fusion zone (FZ) of welded and post-weld heat treated (PWHT) coupons were examined by the use of standard metallographic techniques involving optical microscopy, analytical scanning electron microscopy (SEM) and analytical transmission electron microscopy. Moreover, grain boundary segregation behavior of boron atoms during pre-weld heat treatments was evaluated using secondary ion mass spectroscopic system. In the first phase of the research, 718Plus was welded using a low and high heat input CO2 laser to assess its weld cracking response. Detailed examination of the welds by analytical electron microscopic technique revealed the occurrence of cracking in the HAZ of low heat input welds, while their FZ was crack free. However, both the FZ and HAZ of high heat input welds were crack-free. Resolidified constituents were observed along the cracked grain boundaries of the lower heat input welds, which indicated that HAZ cracking in this newly developed superalloy was associated with grain boundary liquation. However, despite a more extensive liquation of grain boundaries and grain interior in the HAZ of high heat input welds, no cracking occurred. This was attributed to the combination of lower welding stresses generated during cooling, and relaxation of these stresses by thick intergranular liquid. Although HAZ cracking was prevented by welding with a high heat input laser, it resulted in a significant damage to the parent microstructure through its extensive liquation. Thus, the use of low heat input welding is desirable. However, this resulted in HAZ cracking which needs to be minimized or eliminated. Therefore, during the second phase of this research, the effects of pre-weld thermal processing on the cracking response of 718Plus were investigated. Results from the quantification of the cracking of the alloy showed that HAZ cracking may be significantly reduced or eliminated through an adequate selection of pre-weld thermal cycle. In the third stage of this research, crack-free welds of 718Plus were post-weld heat treated using standard thermal schedules. A significant solid state cracking of the alloy occurred during the PWHT. The cracking was attributed to the presence of embrittling phases on HAZ grain boundaries, coupled with aging contraction stresses that are generated by a considerable precipitation of gamma prime phase during aging.

The present dissertation reports the findings of a study of cracking behavior of a newly developed superalloy, Allvac 718Plus during high power beam welding and post-weld heat treatment. Microstructures of the base alloy, heat affected zone (HAZ) and fusion zone (FZ) of welded and post-weld heat treated (PWHT) coupons were examined by the use of standard metallographic techniques involving optical microscopy, analytical scanning electron microscopy (SEM) and analytical transmission electron microscopy. Moreover, grain boundary segregation behavior of boron atoms during pre-weld heat treatments was evaluated using secondary ion mass spectroscopic system. In the first phase of the research, 718Plus was welded using a low and high heat input CO2 laser to assess its weld cracking response. Detailed examination of the welds by analytical electron microscopic technique revealed the occurrence of cracking in the HAZ of low heat input welds, while their FZ was crack free. However, both the FZ and HAZ of high heat input welds were crack-free. Resolidified constituents were observed along the cracked grain boundaries of the lower heat input welds, which indicated that HAZ cracking in this newly developed superalloy was associated with grain boundary liquation. However, despite a more extensive liquation of grain boundaries and grain interior in the HAZ of high heat input welds, no cracking occurred. This was attributed to the combination of lower welding stresses generated during cooling, and relaxation of these stresses by thick intergranular liquid. Although HAZ cracking was prevented by welding with a high heat input laser, it resulted in a significant damage to the parent microstructure through its extensive liquation. Thus, the use of low heat input welding is desirable. However, this resulted in HAZ cracking which needs to be minimized or eliminated. Therefore, during the second phase of this research, the effects of pre-weld thermal processing on the cracking response of 718Plus were investigated. Results from the quantification of the cracking of the alloy showed that HAZ cracking may be significantly reduced or eliminated through an adequate selection of pre-weld thermal cycle. In the third stage of this research, crack-free welds of 718Plus were post-weld heat treated using standard thermal schedules. A significant solid state cracking of the alloy occurred during the PWHT. The cracking was attributed to the presence of embrittling phases on HAZ grain boundaries, coupled with aging contraction stresses that are generated by a considerable precipitation of gamma prime phase during aging.

科学研究費補助金 研究種目:基盤研究(B)(2) 課題番号:08455142 研究代表者:丹司 敬義 研究期間:1996-1997年度

Pour fabriquer le caisson-coeur du futur réacteur expérimental Jules Horowitz (RJH), un assemblage de viroles est effectué à l'aide d'un procédé haute énergie : le soudage par faisceau d'électrons (FE). L'aluminium 6061-T6 qui a été choisi pour la fabrication de ces viroles est un alliage à durcissement structural, ce qui signifie que ses propriétés mécaniques sont très fortement dépendantes de son état de précipitation. Lors du soudage des viroles, l'état microstructural du matériau est affecté : on assiste notamment à une dégradation de l'état fin de précipitation (T6). Les conséquences de cette dégradation microstructurale sont diverses. Notamment, l'évolution de l'état de précipitation au cours du soudage engendre une variation du comportement mécanique et impactera donc la distribution des contraintes résiduelles. De plus, les propriétés mécaniques en service à proximité du joint soudé seront grandement modifiées, on assiste par exemple à une chute de la limite d'élasticité. Dans ce travail, des essais cycliques ont été effectués après des chargements thermiques représentatifs d'une opération de soudage mais aussi pendant des essais isothermes. L'analyse de ces résultats et la confrontation à des mesures de Diffusion de Neutrons aux Petits Angles (DNPA) et de Microscopie Electronique en Transmission (MET) permettent de comprendre les effets de la précipitation sur la loi de comportement de l'alliage. Afin de prédire les évolutions microstructurales et mécaniques dans l'alliage 6061, un logiciel de précipitation a été implémenté et couplé à un modèle élastoplastique à base physique. Les résultats obtenus permettent de représenter la grande variété de comportement observé lors de la campagne expérimentale. Un couplage entre simulation éléments finis thermique et précipitation a été effectué et permet d'ouvrir des perspectives de simulations plus physiques pour ce type d'alliage. / In order to assemble the pressure vessel of experimental Reactor Jules Horowitz (RJH) of France in the future, the electron beam welding process will be used. Several ferrules in a 6061-T6 age hardening aluminum alloy are used for manufacturing this vessel. The fine precipitation state (T6) is affected significantly by the electron beam welding process. Consequently, this microstructural degradation leads to an evolution of the mechanical behaviour and thus will affect the distribution of residual stresses. Moreover, the mechanical properties of the weld joint at ambiant temperature can be modified, such as the yield stress that may drop from 280 MPa to 55 MPa. In this work, cyclic tensile tests have been performed after anisothermal histories representative of welding and during isothermal treatments. The analysis of these results is compared with Small Angles Neutrons Scattering (SANS) and Transmission Electron Microscopy (TEM) characterizations that allow to understand the effect of the precipitation on the material behaviour. To predict the microstructural evolutions in the 6061 structure, a precipitation model has been developped. The precipitation software "PreciSo" coupled with a Finite Element thermal simulations and elastoplastic models allows to open new prospectives in the physical-based simulations domain.

Recently, there has been a growing interest in semiconductor and semiconducting oxide nanowires for applications in electronics, energy conversion, energy storage and optoelectronic devices such as field effect transistors, solar cells, Li- ion batteries, gas sensors, light emitting diodes, field emission displays etc. Semiconductor and semiconducting oxide nanowires have been synthesized widely by different vapor transport methods. However, conditions like high growth temperature, low vacuum, carrier gases for the growth of nanowires, limit the applicability of the processes for the growth of nanowires on a large scale for different applications. In this thesis work, studies have been made on the growth of semiconductor and semiconducting oxide nanowires at a relatively lower substrate temperature (< 500 °C), in a high vacuum (1× 10-5 mbar), without employing any carrier gas, by electron beam and resistive thermal evaporation processes. The morphology, microstructure, and composition of the nanowires have been investigated using analytical techniques such as SEM, EDX, XRD, XPS, and TEM. The optical properties of the films such as reflectance, transmittance in the UV-visible and near IR region were studied using a spectrophotometer. Germanium nanowires were grown at a relatively lower substrate temperature of 380-450 °C on Si substrates by electron beam evaporation (EBE) process using a Au-assisted Vapor-Liquid-Solid mechanism. High purity Ge was evaporated in a high vacuum of 1× 10-5 mbar, and gold catalyst coated substrates maintained at a temperature of 380-450 °C resulted in the growth of germanium nanowires via Au-catalyzed VLS growth. The influence of deposition parameters such as the growth temperature, Ge evaporation rate, growth duration, and gold catalyst layer thickness has been investigated. The structural, morphological and compositional studies have shown that the grown nanowires were single-crystalline in nature and free from impurities. The growth mechanism of Germanium nanowires by EBE has been discussed. Studies were also made on Silicon nanowire growth with Indium and Bismuth as catalysts by electron beam evaporation. For the first time, silicon nanowires were grown with alternative catalysts by the e-beam evaporation method. The use of alternative catalysts such as Indium and Bismuth results in the decrease of nanowire growth temperature compared to Au catalyzed Si nanowire growth. The doping of the silicon nanowires is possible with an alternative catalyst. The second part of the thesis concerns the growth of oxide semiconductors such as SnO2, Sn doped Indium oxide (ITO) nanowires by the electron beam evaporation method. For the first time, SnO2 nanowires were grown with a Au-assisted VLS mechanism by the electron beam evaporation method at a low substrate temperature of 450 °C. SEM, XRD, XPS, TEM, EDS studies on the grown nanowires showed that they were single crystalline in nature and free of impurities. The influence of deposition parameters such as the growth temperature, oxygen partial pressure, evaporation rate of Sn, and the growth duration has been investigated. Studies were also done on the application of SnO2 nanowire films for UV light detection. ITO nanowires were grown via a self-catalytic VLS growth mechanism by electron beam evaporation without the use of any catalyst at a low substrate temperature of 250-400 °C. The influence of deposition parameters such as the growth temperature, oxygen partial pressure, evaporation rate of ITO, and growth duration has been investigated. Preliminary studies have been done on the application of ITO nanowire films for transparent conducting coatings as well as for antireflection coatings. The final part of the work is on the Au-assisted and self catalytic growth of SnO2 and In2O3 nanowires on Si substrates by resistive thermal evaporation. For the first time, SnO2 nanowires were grown with a Au-assisted VLS mechanism by the resistive thermal evaporation method at a low substrate temperature of 450 °C. SEM, XRD, XPS, TEM, and EDS studies on the grown nanowires showed that they were single crystalline in nature and free of impurities. Studies were also made on the application of SnO2 nanowire films for methanol sensing. The self-catalytic growth of SnO2 and In2O3 nanowires were deposited in high vacuum (5×10-5 mbar) by thermal evaporation using a modified evaporation source and a substrate arrangement. With this arrangement, branched SnO2 and In2O3 nanowires were grown on a Si substrate. The influence of deposition parameters such as the applied current to the evaporation boat, and oxygen partial pressure has been investigated. The growth mechanism behind the formation of the branched nanowires as well as nanowires has been explained on the basis of a self-catalytic vapor-liquid-solid growth mechanism. The highlight of this thesis work is employing e-beam evaporation and resistive thermal evaporation methods for nanowire growth at low substrate temperatures of ~ 300-500 °C. The grown nanowires were tested for applications such as gas sensing, transparent conducting coatings, UV light detection and antireflection coating etc. The thesis is divided into nine chapters and each of its content is briefly described below. Chapter 1 In this chapter, a brief introduction is given on nanomaterials and their applications. This chapter also gives an overview of the different techniques and different growth mechanisms used for nanowires growth. A brief overview of the applications of semiconductors and semiconductor oxide nanowires synthesized is also presented. Chapter 2 Different experimental techniques employed for the growth of Si, Ge, SnO2, In2O3, ITO nanowires have been described in detail in this chapter. Further, the details of the different techniques employed for the characterization of the grown nanowires were also presented. Chapter 3 In this chapter, studies on the growth of Germanium nanowires by electron beam evaporation (EBE) are given. The influence of deposition parameters such as growth temperature, evaporation rate of germanium, growth duration, and catalyst layer thickness was investigated. The morphology, structure, and composition of the nanowires were investigated by XRD, SEM, and TEM. The VLS growth mechanism has been discussed for the formation of the germanium nanowires by EBE using Au as a catalyst. Chapter 4 This chapter discusses the growth of Si nanowires with Indium and Bismuth as an alternate to Au-catalyst by electron beam evaporation. The influence of deposition parameters such as growth temperature, Si evaporation rate, growth duration, and catalyst layer thickness has been investigated. The grown nanowires were characterized using XRD, SEM, TEM and HRTEM. The Silicon nanowires growth mechanism has been discussed. Chapter 5 This chapter discusses the Au-catalyzed VLS growth of SnO2 nanowires by the electron beam evaporation method as well as Antimony doped SnO2 nanowires by co-evaporation method at a low substrate temperature of 450 °C. The grown nanowires were characterized using XRD, SEM, TEM, STEM, Elemental mapping, HRTEM, and XPS. The effect of deposition parameters such as oxygen partial pressure, growth temperature, catalyst layer thickness, evaporation rate of Sn, and the growth duration of nanowires were investigated. The SnO2 nanowires growth mechanism has been explained. Preliminary studies were made on the possible use of pure SnO2 and doped SnO2 nanowire films for UV light detection. SnO2 nanowire growth on different substrates such as stainless steel foil (SS), carbon nanosheets films, and graphene oxide films were studied. SnO2 nanowire growth on different substrates, especially SS foil will be useful for Li-ion battery applications. Chapter 6 This chapter discusses the self catalyzed VLS growth of Sn doped Indium oxide (ITO) nanowires by the electron beam evaporation method at a low temperature of 250-400 °C. The grown nanowires were characterized using XRD, SEM, TEM, STEM, HRTEM, and XPS. The effect of deposition parameters such as oxygen partial pressure, growth temperature, evaporation rate of ITO, and the growth duration of the nanowires were investigated. Preliminary studies were also made on the possible use of self-catalyzed ITO nanowire films for transparent conducting oxides and antireflection coatings. ITO nanowire growth on different and large area substrates such as stainless steel foil (SS), and Glass was done successfully. ITO nanowire growth on different substrates, especially large area glass substrates will be useful for optoelectronic devices. Chapter 7 In this chapter, studies on the growth of SnO2 nanowires by a cost-effective resistive thermal evaporation method at a relatively lower substrate temperature of 450 °C are presented. The grown nanowires were characterized using XRD, SEM, TEM, HRTEM, and XPS. Preliminary studies were done on the possible use of SnO2 nanowire films for methanol sensing. Chapter 8 This chapter discusses the self-catalytic growth of SnO2 and In2O3 nanowires by resistive thermal evaporation. The nanowires of SnO2 and In2O3 were grown at low temperatures by resistive thermal evaporation using a modified source and substrate arrangement. In this arrangement, branched SnO2 nanowires, and In2O3 nanowires growth was observed. The grown nanowires were characterized using XRD, SEM, TEM, HRTEM, and XPS. The possible growth mechanism for branched nanowires growth has been explained. Chapter 9 The significant results obtained in the present thesis work have been summarized in this chapter.

[ES] El cuidado de la salud es un campo en el que la detección precoz de enfermedades está cobrando cada vez más importancia. Hoy en día, profesionales y ciudadanos demandan que las técnicas de diagnóstico sean de alta calidad, tanto para el sistema de sanidad privado como para el público. Cuando se utilizan técnicas de diagnóstico de manera inadecuada, eso puede acarrear bastantes consecuencias, tales como un serio peligro sobre la salud y la sobrecarga técnica y económica de los servicios de salud. Eso es debido a que las técnicas de diagnóstico disponibles hoy en día son demasiado costosas, centralizadas en laboratorios y necesitan profesionales altamente cualificados para poder llevar a cabo dichas tareas, lo que conllevaría una demora en el tiempo, siendo este muchas veces vital para los enfermos. Es muy necesario, por lo tanto, reflexionar sobre la necesidad y emergencia de tales prácticas preventivas, especialmente para enfermedades de alto riesgo como el cáncer, el Alzheimer o la primera causa de muerte en el mundo, las enfermedades cardiovasculares. En este contexto, el objetivo principal del trabajo realizado durante esta Tesis Doctoral es ayudar a superar estos problemas mediante la exploración de la posibilidad de utilizar tecnología fotónica para el desarrollo de sistemas de análisis que puedan ser utilizados para el diagnóstico y pronóstico de las enfermedades cardiovasculares. Este objetivo se ha abordado mediante la combinación de la tecnología nanofotónica, consistiendo en la nanofabricación de las estructuras PBG de sensado que ofrece varios beneficios, como una alta sensibilidad, una extrema reducción de tamaño y un proceso de fabricación compatible con el de la industria microelectrónica, con un método de biofuncionalización obteniendo una capa de bioreconocimiento estable y selectiva mediante el uso de la reacción TEC asistida por luz capaz de proporcionar unas capas de bio-reconocimiento extremadamente finas con una inmovilización espacialmente selectiva. / [CAT] L'atenció a la salut és un camp en què la detecció precoç de malalties està cobrant cada vegada més importància. Hui en dia, professionals i ciutadans demanen que les tècniques de diagnòstic siguin d'alta qualitat, tant per al sistema de sanitat privat com per al públic. Quan s'utilitzen tècniques de diagnòstic de manera inadequada, això pot comportar bastants conseqüències, com ara, un seriós perill sobre la salut i la sobrecàrrega tècnica i econòmica dels serveis de salut. Això és degut al fet que les tècniques de diagnòstic disponibles hui en dia són molt costoses, centralitzades en laboratoris i necessiten professionals altament qualificats per poder realitzar aquestes tasques, lo que comportaria a una demora en el temps que moltes vegades es vital pels malalts. És molt necessari, per tant, reflexionar sobre la necessitat i emergència de tals practiques preventives, especialment per a malalties d'alt risc com el càncer, l'Alzheimer o la primera causa de mort al món, les malalties cardiovasculars. En aquest context, l'objectiu principal del treball realitzat durant aquesta Tesi Doctoral és ajudar a superar aquests problemes mitjançant l'exploració de la possibilitat d'utilitzar tecnologia fotònica per al desenvolupament de sistemes d'anàlisis que puguin ser utilitzats per al diagnòstic i pronòstic de les malalties cardiovasculars. Aquest objectiu s'ha abordat mitjançant la combinació de la tecnologia nanofotònica, consistint en la nanofabricació de les estructures de detecció de PBG fotòniques que ofereix diversos beneficis, com una alta sensibilitat, una extrema reducció de mida i un procés de fabricació compatible amb el de la indústria microelectrònica, amb un mètode de biofuncionalització obtenint una capa de bio-reconeixement estable i selectiva mitjançant l'ús de la reacció TEC assistida per llum capaç de proporcionar unes capes de bioreconeixement extremadament fines amb una immobilització espacialment selectiva. preventives, especialment per a malalties d'alt risc com el càncer, l'Alzheimer o la primera causa de mort al món, les malalties cardiovasculars. En aquest context, l'objectiu principal del treball realitzat durant aquesta Tesi Doctoral és ajudar a superar aquests problemes mitjançant l'exploració de la possibilitat d'utilitzar tecnologia fotònica per al desenvolupament de sistemes d'anàlisis que puguin ser utilitzats per al diagnòstic i pronòstic de les malalties cardiovasculars. Aquest objectiu s'ha abordat mitjançant la combinació de la tecnologia nanofotònica, consistint en la nanofabricació de les estructures de detecció de PBG fotòniques que ofereix diversos beneficis, com una alta sensibilitat, una extrema reducció de mida i un procés de fabricació compatible amb el de la indústria microelectrònica, amb un mètode de biofuncionalització obtenint una capa de bio-reconeixement estable i selectiva mitjançant l'ús de la reacció TEC assistida per llum capaç de proporcionar unes capes de bioreconeixement extremadament fines amb una immobilització espacialment selectiva. / [EN] Healthcare is a field where the early detection of diseases is becoming more and more important. Nowadays, professionals and citizens demand high quality diagnosis techniques offered by both private and public health systems. When the application of diagnostic tests is not adequate, different consequences can be observed such as health hazard and technical and economic overload of health services. This is due to the fact that the diagnostic techniques available are expensive, centralized in laboratories and with the need for highly qualified professionals to carry out these tasks, what can fundamentally lead to delays in time, being critical for the patient's health. It is very necessary, therefore, to reflect on the need and emergency of such preventive practices, especially for high-risk diseases such as cancer, Alzheimer or the first cause of death in the world, the cardiovascular diseases. Within this context, the main objective of the work done during this PhD Thesis is to help on overcoming these problems by exploring the possibility of using photonic technology for the development of analysis devices which might be used for the early diagnosis and prognosis of cardiovascular diseases. This objective has been addressed by combining nanophotonic technology, by the nanofabrication of the photonic PBG sensing structures, which provides several benefits such as a high sensitivity, an extreme size reduction and a fabrication process being compatible with that from the microelectronics industry, with a light-assisted biofunctionalization method forming a stable and selective biorecognition layer using TEC reaction able to provide extremely thin biorecognition layers with a spatially-selective immobilization. / Sabek, J. (2019). Combination of nanophotonic biosensors and light-assisted immobilization procedures for the detection of cardiac biomarkers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124821 / TESIS

First part of this thesis is a theoretical essay which deals with the basics of the variable pressure scanning electron microscope, includes detection of secondary electrons with a view to a scintillation detector. The first applied part of the thesis is focused on prediction, measuring and setting-up optional working parley in vacuum electrodes scintillation detector system, with a stress small diameter hole in screenings C1 and C2. Second applied part was verify a change of working distance between sample and detector in consequence to optional solution for another work.