This dissertation presents a unique concept for a device architecture named the nanotube (NT) architecture, which is capable of higher drive current compared to the Gate-All-Around Nanowire architecture when applied to heterostructure Tunnel Field Effect Transistors. Through the use of inner/outer core-shell gates, heterostructure NT TFET leverages physically larger tunneling area thus achieving higher driver current (ION) and saving real estates by eliminating arraying requirement. We discuss the physics of p-type (Silicon/Indium Arsenide) and n-type (Silicon/Germanium hetero-structure) based TFETs. Numerical TCAD simulations have shown that NT TFETs have 5x and 1.6 x higher normalized ION when compared to GAA NW TFET for p and n-type TFETs, respectively. This is due to the availability of larger tunneling junction cross sectional area, and lower Shockley-Reed-Hall recombination, while achieving sub 60 mV/dec performance for more than 5 orders of magnitude of drain current, thus enabling scaling down of Vdd to 0.5 V. This dissertation also introduces a novel thin-film-transistors architecture that is named the Wavy Channel (WC) architecture, which allows for extending device width by integrating vertical fin-like substrate corrugations giving rise to up to 50% larger device width, without occupying extra chip area. The novel architecture shows 2x higher output drive current per unit chip area when compared to conventional planar architecture. The current increase is attributed to both the extra device width and 50% enhancement in field effect mobility due to electrostatic gating effects. Digital circuits are fabricated to demonstrate the potential of integrating WC TFT based circuits. WC inverters have shown 2× the peak-to-peak output voltage for the same input, and ~2× the operation frequency of the planar inverters for the same peak-to-peak output voltage. WC NAND circuits have shown 2× higher peak-to-peak output voltage, and 3× lower high-to-low propagation delay times when compared to their planar counterparts. WC NOR circuits have shown 70% higher peak-to-peak output voltage, over their planar counterparts. Finally, a WC based pass transistor logic multiplexer circuit is demonstrated, which has shown more than 5× faster high-to-low propagation delay compared to its planar counterpart at a similar peak-to-peak output voltage.

This thesis deals with study homogeneity of thin organic layers using image analysis. The theoretical parts deal with preparation thin layers and some methods examining their surface, especially optical microscopy and profilometry. Optical microscope NIKON ECLIPSE E200, digital camera NIKON 5400 and computer was used for study homogeneity of organic layers by image analysis. Images of the organic layer and single electrodes, which were steamed on organic layer, were surveyed. Homogeneity of surfaces layers was assessed by errors related with common moments (roughness average, root mean square roughness, skewness, and kurtosis). Differences between single samples in connection with size their common moments and homogeneity are discussed at the close of this work.

This diploma thesis deals with the automation of the deposition process by ion beam sputtering and ion beam assisted deposition. This work contains drawings of mechanical adjustments of the deposition chamber designed to control shutter and rotation of the target using stepper motors. There are presented ways to control stepper motors and troubleshoot their exact settings. Another task is to design a system for computer control of the deposition process. There are discussed ways to control the ion sources, pressure meter, flow meter and thickness meter, and their connection to a PC via RS-232 and analog-digital converters. It is also designed control program in LabVIEW, which allow automated multilayer deposition. Last part of the thesis deals with testing automatic deposition and results are commented.

Les recherches sur les matériaux en couches minces dédiées à l'industrie solaire restent un sujet d'intérêt avec le nombre croissant de types de matériaux incorporés en tant qu'absorbeur dans un dispositif solaire. Le besoin de techniques de caractérisation est donc aigu pour l'optimisation des matériaux et leur incorporation dans des cellules photovoltaïques. Dans cette thèse, une méthode de photo-courant basée sur la spectroscopie de photo-courant à transformée de Fourier (FTPS) est utilisée pour effectuer des mesures sur des matériaux en couches minces et des cellules solaires. Notre FTPS a été développée pour réaliser 3 types de mesures: 1.) mesure de réflexion et de transmission (R/T), 2.) spectroscopie du coefficient d'absorption, et 3.) mesure de réponse spectrale, efficacité quantique externe et densité de photo-courant court-circuit. Cette dernière est spécifiquement utilisée pour les cellules solaires. Nous avons utilisé les résultats de R/T pour effectuer une simulation numérique donnant l'épaisseur, l'indice de réfraction, la rugosité du film et le coefficient d'absorption optique. Une modélisation de la densité d'états (DOS) en utilisant le logiciel DeOSt automatisé avec l'algorithme TLBO (Teacher Learner Based Optimization) a été développée pour trouver les valeurs des paramètres de DOS les mieux adaptées afin de reproduire le ∝ expérimental. Une analyse de sensibilité a été faite pour trouver les paramètres DOS les plus importants parmi 15-17 paramètres. Nous avons mesuré plusieurs échantillons de a-Si: H déposés sous différentes conditions de dépôt, et utilisé nos résultats pour étudier leur DOS. Une comparaison des mesures de α sur a-Si: H déposé sur un substrat de verre et incorporé dans une cellule solaire a également été réalisée. Cette étude a conclu qu'une correction du spectre de coefficient d'absorption doit être effectuée pour les mesures sur les cellules solaires. / Investigations on thin film materials dedicated to the solar industry are still a matter of interest with the growing numbers of material types incorporated as absorbers in a solar cell device. The need of characterization techniques is therefore acute for the optimization of materials and their incorporation in solar devices. In this thesis, a photocurrent method based on Fourier Transform Photocurrent Spectroscopy (FTPS) is used to perform the measurements of thin film materials and solar cells. Our FTPS was further developed to perform 3 types of measurements: 1.) reflection and transmission (R/T) measurement, 2.) absorption coefficient spectroscopy and 3.) spectral response, external quantum efficiency, and short circuit photocurrent density measurements. This latter is specifically used for solar cells. We used the R/T results to perform numerical simulations giving the thickness, refractive index, film roughness, and optical absorption coefficient. A modeling of the density of states (DOS) using the software DeOSt automated with the Teacher Learner Based Optimization (TLBO) algorithm was achieved to find the best suited DOS parameter values to reproduce the experimental spectrum of alpha. A sensitivity analysis was performed to find the most important DOS parameters among 15-17 parameters. For the experimental studies, we have measured several a-Si:H thin film samples prepared under different deposition conditions, and used their absorption coefficient; spectra to study their DOS. A comparison of absorption coefficient; measurements on a-Si:H thin films deposited on a glass substrate and incorporated in a solar cell device stack was also conducted. This study concluded that a correction of the absorption coefficient spectrum measured on solar cells had to be done.

Since the discovery of size-selective metal-organic frameworks (MOF) researchers have tried to manufacture them into gas separation membranes. ZIF-8 became the most studied MOF for membrane applications mainly because of its simple synthesis, good chemical and thermal stability, recent commercial availability and attractive pore size. The aim of this work is to develop convenient methods for growing ZIF thin layers on polymer supports to obtain defect-free ZIF membranes with good gas separation properties. We present new approaches for ZIF membranes preparation on polymers. We introduce zinc oxide nanoparticles in the support as a secondary metal source for ZIF-8 growth. Initially the ZnO particles were incorporated into the polymer matrix and later on the surface of the polymer by magnetron sputtering. In both cases, the ZnO facilitated to create more nucleation opportunities and improved the ZIF-8 growth compared to the synthesis without using ZnO. By employing the secondary seeded growth method, we were able to obtain thin (900 nm) ZIF-8 layer with good gas separation performance. Next, we propose a metal-chelating polymer as a suitable support for growing ZIF layers. Defect-free ZIF-8 films with a thickness of 600 nm could be obtained by a contra-diffusion method. ZIF-8 membranes were tested for permeation of hydrogen and hydrocarbons, and one of the highest selectivities reported so far for hydrogen/propane, and propylene/propane was obtained. Another promising method to facilitate the growth of MOFs on polymeric supports is the chemical functionalization of the support surface with functional groups, which can complex metal ions and which can covalently bond the MOF crystals. We functionalized the surface of a common porous polymeric membrane with amine groups, which took part in the reaction to form ZIF-8 nanocrystals. We observed an enhancement in adhesion between the ZIF layer and the support. The effect of parameters of the contra-diffusion experiment (such as temperature lower than room temperature and synthesis times shorter than 1 hour) on ZIF-8 membrane properties was evaluated. We could prepare one of the thinnest (around 200 nm) yet selective ZIF-8 films reported.

<div> <p>Thermal processing is a critical step in shelf-stable food manufacturing to the ensure safety of the food products. To accurately model and establish the thermal processes, temperature-dependent thermal properties are needed. Existing methods for measuring the temperature-dependent thermal diffusivity (α), thermal conductivity (k) and volumetric heat capacity (C) are time consuming, tend to have high errors, and cannot provide results in a single experiment, especially at temperatures above 100°C. A novel bench scale device, named Thermal Properties Cell (TPCell), was custom made to rapidly estimate the temperature-dependent thermal parameters of food products. </p> <p> </p> <p>The TPCell used thin film heaters as the heating elements. The first study focused on estimating the thermal properties of a thin film heater. Using mathematical modeling and sequential parameter estimation, the effective thermal diffusivity of the thin film heater was found at different temperatures. The estimated thermal properties of the thin film heater were used for the second study.</p> <p> </p> <p>The objective of the second study was to design optimal complementary experiments using TPCell. Complementary experiments are a combination of experiments that enable estimation of multiple thermal parameters from the experimental temperature data, based on sensitivity analysis. Sensitivity coefficients indicate the extent of change in a measured variable due to a change in value of an input parameter. Designs of experiments were simulated and their impact on sensitivity and optimality criteria was analyzed. Results from the simulated profiles were validated using sweet potato puree. </p> <p> </p> <p>Learnings from this work can be directly applied for the optimization of all types of food thermal processes, including retort and aseptic processing. Optimally designed processes increase preservation of the heat labile nutrients, color, flavor, and taste compounds, thereby enhancing the quality of food products.</p> </div> <br>

Nanomagnetic devices are highly energy efficient and non-volatile. Because of these two attributes, they are potential replacements to many currently used information processing technologies, and they have already been implemented in many different applications. This dissertation covers a study of nanomagnetic devices and their applications in various technologies for information processing – from simulating and analyzing the mechanisms behind the operation of the devices, to experimental investigations encompassing magnetic film growth for device components to nanomagnetic device fabrication and measurement of their performance. Theoretical sections of this dissertation include simulation-based modeling of perpendicular magnetic anisotropy magnetic tunnel junctions (p-MTJ) and low energy barrier nanomagnets (LBM) – both important devices for magnetic device-based information processing. First, we propose and analyze a precessionally switched p-MTJ based memory cell where data is written without any on-chip magnetic field that dissipates energy as low as 7.1 fJ. Next, probabilistic (p-) bits implemented with low energy barrier nanomagnets (LBMs) are also analyzed through simulations, and plots show that the probability curves are not affected much by reasonable variations in either thickness or lateral dimensions of the magnetic layers. Experimental sections of this dissertation comprise device fabrication aspects from the basics of material deposition to the application-based demonstration of an extreme sub-wavelength electromagnetic antenna. Magnetic tunnel junctions for memory cells and low barrier nanomagnets for probabilistic computing, in particular, require ultrathin ferromagnetic layers of uniform thickness, and non-uniform growth or variations in layer thickness can cause failures or other problems. Considerable attention was focused on developing methodologies for uniform thin film growth. Lastly, micro- and nano-fabrication methods are used to build an extreme sub-wavelength electromagnetic antenna implemented with an array of magnetostrictive nanomagnets elastically coupled to a piezoelectric substrate. The 50 pW signal measured from the approximately 250,000-nanomagnet antenna sample was 10 dB above the noise floor.

The temperature and field dependence of the magnetization of epitaxial, undoped anatase TiO2 thin films on SrTiO3 substrates was investigated. Low-energy ion irradiation was used to modify the surface of the films within a few nanometers, yet with high enough energy to produce oxygen and titanium vacancies. The as-prepared thin film shows ferromagnetism which increases after irradiation with low-energy ions. An optimal and clear magnetic anisotropy was observed after the first irradiation, opposite to the expected form anisotropy. Taking into account the experimental parameters, titanium vacancies as di-Frenkel pairs appear to be responsible for the enhanced ferromagnetism and the strong anisotropy observed in our films. The magnetic impurities concentrations was measured by particle-induced X-ray emission with ppm resolution. They are ruled out as a source of the observed ferromagnetism before and after irradiation.

Title: Preparation of Nanocomposites of Metal Oxides in Plasma Polymer and Study of Their Properties Author: Oleksandr Polonskyi Department: Department of Macromolecular Physics, MFF UK Supervisor of the doctoral thesis: Prof. RNDr. Hynek Biederman, DrSc. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This thesis is devoted to a study of nanocomposite films Al (Al oxide)/plasma polymer prepared by various techniques using magnetron sputtering, plasma polymerization and cluster beam deposition. The formation and deposition of metal/metal oxide nanoclusters using a gas aggregation cluster source (GAS) was also considered. The role of low concentration of oxygen in the aggregation gas on the process of Al and Ti cluster deposition was studied. Properties of the nanoclusters and nanocomposite films were characterized by various techniques. Morphology of the nanocomposites was examined by AFM, TEM or HRTEM and SEM. Elemental analysis and chemical composition of the films were studied by XPS and FTIR. Optical characterization of the prepared films was done by UV-Vis spectroscopy and spectroscopic ellipsometry. It has been shown that using GAS nanocomposite Al(AlxOy)/C:H may be prepared. Keywords: nanocomposite thin film, plasma polymer, metal...

Title: Plasma polymers in the nanostructured and nanocomposite coatings Author: Artem Shelemin Department / Institute: Department of the Macromolecular Physics Supervisor of the doctoral thesis: Prof. RNDr. Hynek Biederman, DrSc. Abstract: The thesis represents the main results of my research work aimed to study nanostructured and nanocomposite films of plasma polymer. A few alternative experimental approaches were developed and investigated which ranged from low pressure (gas aggregation cluster sources and glancing angle deposition) to atmospheric pressure (dielectric barrier discharge and plasma jet) plasma processing. The metal/metal oxide Ti/TiOx, AlOx and plasma polymer SiOx(CH), Nylon 6,6 nanoparticles were prepared. The analysis of morphology of deposited plasma polymer coatings was performed by AFM and SEM. The chemical composition of films was studied by XPS and FTIR. Keywords: plasma polymer, nanoparticle, thin film, nanostructures