Download or read book Mechanisms for Intrinsic Stress Evolution During and After Polycrystalline Film Growth written by Hang Yu (Ph. D.) and published by . This book was released on 2013 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growth of polycrystalline films involves poorly understood kinetic processes that occur far from equilibrium and lead to complex co-evolution of the surface, microstructure and intrinsic stress of the films. Here we present a comprehensive study consisting of in situ stress measurements, microstructure characterization, and analytical modeling for various polycrystalline systems. We find that in systems of high atomic mobility, the stress change after polycrystalline film growth can be attributed to a fast reversible surface process and a slow irreversible bulk process. The fast process is weakly dependent on temperature and is associated with changes in the shape of grain surfaces. The slow process is strongly dependent on temperature and is mostly associated with grain growth in the bulk of the film. We also discovered a turnaround phenomenon in which, under conditions of intermediate atomic mobility, the stress evolves from a tensile toward a compressive state, and then turns around to evolve toward a tensile state. This stress turnaround phenomenon is strongly dependent on the substrate temperature and deposition rate, and can be attributed to an increase of the grain size during film deposition. Grain growth during deposition not only leads to a tensile component of the intrinsic stress, but also changes the grain size dependence of the compressive component. The compressive component results from incorporation of excess adatoms in grain boundaries, and the magnitude of the compressive stress is controlled by a competition between adatom incorporation in 2D islands and incorporation at grain boundaries. We also investigated the effect of the angle of incidence of the flux of depositing atoms on stress and structure evolution during polycrystalline film growth. We find that as the angle of incidence increases, the coalescence thickness increases and the stress becomes less compressive or more tensile. We attribute these phenomena to the enhanced surface roughness, the shadowing effect, the steering effect and the presence of Ehrlich-Schwoebel barriers during oblique angle deposition. All these effects lead to suppression of the adatom-grain boundary incorporation process. Based on this thesis work, intrinsic stresses in polycrystalline films can be categorized into three types: Type I, the intermediate type and Type II. These behaviors are observed in systems of low, intermediate and high atomic mobility, respectively. Compressive stresses develop in Type II behavior and tensile stresses develop in Type I behavior. The transition of the stress behavior from Type I, to the intermediate type and to Type II is continuous and can be achieved by adjusting deposition conditions. Whether the post-coalescence stress is tensile, or compressive, or evolving from compressive to tensile depends on the homologous temperature, the deposition rate and the angle of the incidence of the flux of depositing atoms.

Download or read book Understanding Intrinsic Stress Evolution in Polycrystalline Thin Films that Grow by the Volmer Weber Method written by Ashok Rajamani and published by . This book was released on 2003 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thin Film Materials written by L. B. Freund and published by Cambridge University Press. This book was released on 2004-01-08 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin film mechanical behavior and stress presents a technological challenge for materials scientists, physicists and engineers. This book provides a comprehensive coverage of the major issues and topics dealing with stress, defect formation, surface evolution and allied effects in thin film materials. Physical phenomena are examined from the continuum down to the sub-microscopic length scales, with the connections between the structure of the material and its behavior described. Theoretical concepts are underpinned by discussions on experimental methodology and observations. Fundamental scientific concepts are embedded through sample calculations, a broad range of case studies with practical applications, thorough referencing, and end of chapter problems. With solutions to problems available on-line, this book will be essential for graduate courses on thin films and the classic reference for researchers in the field.

Download or read book Stress Evolution During Volmer Weber Thin Film Growth written by Juan S. Tello and published by . This book was released on 2008 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stress evolution in polycrystalline thin solid films that grow by the Volmer Weber mechanism is studied numerically by means of an adaptive finite element model. The model tracks the shape of an array of islands as they grow and coalesce into a continuous film, changing shape as a result of a deposition flux, as well as surface and grain boundary diffusion. Stress is generated in the film as a result of forces exerted between neighboring islands as they meet to form a grain boundary. The internal stresses in the islands and the diffusive changes on their surfaces and grain boundaries are computed using a coupled finite element scheme. Interactions between neighboring islands are modeled using a cohesive zone law. The model predicts stress-thickness vs thickness behavior that is in excellent agreement with experiments. Specifically, it exhibits a three-stage growth process consisting of a stress-free pre-coalescence stage, a rapid tensile rise at coalescence, and an eventual transition to a steady-state. The steady state stress may be tensile or compressive, depending on the deposition rate, the grain size, and the properties of the film. Detailed parametric studies are conducted to establish the influence of material properties and growth conditions on the stress history, and the results are compared with experimental observations and previous models dating back to 1976. One of the limitations of the model is its inability to accurately capture atomistic behavior near the triple junction region. In light of this, a framework for coupling models of physical problems involving diffusion in a continuum region with one treated using a discrete formulation is presented. This methodology could potentially be used to couple the continuum description of stresses in thin films presented here with say, a Kinetic Monte Carlo simulation of the atomistics in and around the triple junction.

Download or read book Nanostructured Surfaces and Thin Films Synthesis by Physical Vapor Deposition written by Rafael Alvarez and published by MDPI. This book was released on 2021-04-22 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue deals with the synthesis of nanostructured surfaces and thin films by means of physical vapor deposition techniques such as pulsed laser deposition, magnetron sputtering, HiPIMS, or e-beam evaporation, among others. The nanostructuration of the surface modifies the way a material interacts with the environment, changing its optical, mechanical, electrical, tribological, or chemical properties. This can be applied in the development of photovoltaic cells, tribological coatings, optofluidic sensors, or biotechnology to name a few. This issue includes research presenting novel or improved applications of nanostructured thin films, such as photovoltaic solar cells, thin-film transistors, antibacterial coatings or chemical and biological sensors, while also studying the nanostructuration mechanisms, from a fundamental point of view, that produce rods, columns, helixes or hexagonal grids at the nanoscale.

Download or read book Sputtered Thin Films written by Frederick Madaraka Mwema and published by CRC Press. This book was released on 2021-04-12 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sputtered Thin Films: Theory and Fractal Descriptions provides an overview of sputtered thin films and demystifies the concept of fractal theory in analysis of sputtered thin films. It simplifies the use of fractal tools in studying the growth and properties of thin films during sputtering processes. Part 1 of the book describes the basics and theory of thin film sputtering and fractals. Part 2 consists of examples illustrating specific descriptions of thin films using fractal methods. Discusses thin film growth, structure, and properties Covers fractal theory Presents methods of fractal measurements Offers typical examples of fractal descriptions of thin films grown via magnetron sputtering processes Describes application of fractal theory in prediction of thin film growth and properties This reference book is aimed at engineers and scientists working across a variety of disciplines including materials science and metallurgy as well as mechanical, manufacturing, electrical, and biomedical engineering.

Download or read book Thin metal films on weakly interacting substrates written by Andreas Jamnig and published by Linköping University Electronic Press. This book was released on 2020-09-30 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vapor-based growth of thin metal films with controlled morphology on weakly-interacting substrates (WIS), including oxides and van der Waals materials, is essential for the fabrication of multifunctional metal contacts in a wide array of optoelectronic devices. Achieving this entails a great challenge, since weak film/substrate interactions yield a pronounced and uncontrolled 3D morphology. Moreover, the far-from-equilibrium nature of vapor-based film growth often leads to generation of mechanical stress, which may further compromise device reliability and functionality. The objectives of this thesis are related to metal film growth on WIS and seek to: (i) contribute to the understanding of atomic-scale processes that control film morphological evolution; (ii) elucidate the dynamic competition between nanoscale processes that govern film stress generation and evolution; and (iii) develop methodologies for manipulating and controlling nanoscale film morphology between 2D and 3D. Investigations focus on magnetron sputter-deposited Ag and Cu films on SiO2 and amorphous carbon (a-C) substrates. Research is conducted by strategically combining of in situ and real-time film growth monitoring, ex situ chemical and (micro)-structural analysis, optical modelling, and deterministic growth simulations. In the first part, the scaling behavior of characteristic morphological transition thicknesses (i.e., percolation and continuous film formation thickness) during growth of Ag and Cu films on a-C are established as function of deposition rate and temperature. These data are interpreted using a theoretical framework based on the droplet growth theory and the kinetic freezing model for island coalescence, from which the diffusion rates of film forming species during Ag and Cu growth are estimated. By combining experimental data with ab initio molecular dynamics simulations, diffusion of multiatomic clusters, rather than monomers, is identified as the rate-limiting structure-forming process. In the second part, the effect of minority metallic or gaseous species (Cu, N2, O2) on Ag film morphological evolution on SiO2 is studied. By employing in situ spectroscopic ellipsometry, it is found that addition of minority species at the film growth front promotes 2D morphology, but also yields an increased continuous-layer resistivity. Ex situ analyses show that 2D morphology is favored because minority species hinder the rate of coalescence completion. Hence, a novel growth manipulation strategy is compiled in which minority species are deployed with high temporal precision to selectively target specific film growth stages and achieve 2D morphology, while retaining opto-electronic properties of pure Ag films. In the third part, the evolution of stress during Ag and Cu film growth on a-C and its dependence on growth kinetics (as determined by deposition rate, substrate temperature) is systematically investigated. A general trend toward smaller compressive stress magnitudes with increasing temperature/deposition rate is found, related to increasing grain size/decreasing adatom diffusion length. Exception to this trend is found for Cu films, in which oxygen incorporation from the residual growth atmosphere at low deposition rates inhibits adatom diffusivity and decreases the magnitude of compressive stress. The effect of N2 on stress type and magnitude in Ag films is also studied. While Ag grown in N2-free atmosphere exhibits a typical compressive-tensile-compressive stress evolution as function of thickness, addition of a few percent of N2 yields to a stress turnaround from compressive to tensile stress after film continuity which is attributed to giant grain growth and film roughening. The overall results of the thesis provide the foundation to: (i) determine diffusion rates over a wide range of WIS film/substrates systems; (ii) design non-invasive strategies for multifunctional contacts in optoelectronic devices; (iii) complete important missing pieces in the fundamental understanding of stress, which can be used to expand theoretical descriptions for predicting and tuning stress magnitude. La morphologie de films minces métalliques polycristallins élaborés par condensation d’une phase vapeur sur des substrats à faible interaction (SFI) possède un caractère 3D intrinsèque. De plus, la nature hors équilibre de la croissance du film depuis une phase vapeur conduit souvent à la génération de contraintes mécaniques, ce qui peut compromettre davantage la fiabilité et la fonctionnalité des dispositifs optoélectroniques. Les objectifs de cette thèse sont liés à la croissance de films métalliques sur SFI et visent à: (i) contribuer à une meilleure compréhension des processus à l'échelle atomique qui contrôlent l'évolution morphologique des films; (ii) élucider les processus dynamiques qui régissent la génération et l'évolution des contraintes en cours de croissance; et (iii) développer des méthodologies pour manipuler et contrôler la morphologie des films à l'échelle nanométrique. L’originalité de l’approche mise en œuvre consiste à suivre la croissance des films in situ et en temps réel par couplage de plusieurs diagnostics, complété par des analyses microstructurales ex situ. Les grandeurs mesurées sont confrontées à des modèles optiques et des simulations atomistiques. La première partie est consacrée à une étude de comportement d’échelonnement des épaisseurs de transition morphologiques caractéristiques, à savoir la percolation et la continuité du film, lors de la croissance de films polycristallins d'Ag et de Cu sur carbone amorphe (a-C). Ces grandeurs sont examinées de façon systématique en fonction de la vitesse de dépôt et de la température du substrat, et interprétées dans le cadre de la théorie de la croissance de gouttelettes suivant un modèle cinétique décrivant la coalescence d’îlots, à partir duquel les coefficients de diffusion des espèces métalliques sont estimés. En confrontant les données expérimentales à des simulations par dynamique moléculaire ab initio, la diffusion de clusters multiatomiques est identifiée comme l’étape limitante le processus de croissance. Dans la seconde partie, l’incorporation, et l’impact sur la morphologie, d’espèces métalliques ou gazeuses minoritaires (Cu, N2, O2) lors de la croissance de film Ag sur SiO2 est étudié. A partir de mesures ellipsométriques in situ, on constate que l'addition d'espèces minoritaires favorise une morphologie 2D, entravant le taux d'achèvement de la coalescence, mais donne également une résistivité accrue de la couche continue. Par conséquent, une stratégie de manipulation de la croissance est proposée dans laquelle des espèces minoritaires sont déployées avec une grande précision temporelle pour cibler sélectivement des stades de croissance de film spécifiques et obtenir une morphologie 2D, tout en conservant les propriétés optoélectroniques des films d’Ag pur. Dans la troisième partie, l'évolution des contraintes résiduelles lors de la croissance des films d'Ag et de Cu sur a-C et leur dépendance à la cinétique de croissance est systématiquement étudiée. On observe une tendance générale vers des amplitudes de contrainte de compression plus faibles avec une augmentation de la température/vitesse de dépôt, liée à l'augmentation de la taille des grains/à la diminution de la longueur de diffusion des adatomes. Également, l’ajout dans le plasma de N2 sur le type et l'amplitude des contraintes dans les films d'Ag est étudié. L'ajout de quelques pourcents de N2 en phase gaz donne lieu à un renversement de la contrainte de compression et une évolution en tension au-delà de la continuité du film. Cet effet est attribué à une croissance anormale des grains géants et le développement de rugosité de surface. L’ensemble des résultats obtenus dans cette thèse fournissent les bases pour: (i) déterminer les coefficients de diffusion sur une large gamme de systèmes films/SFI; (ii) concevoir des stratégies non invasives pour les contacts multifonctionnels dans les dispositifs optoélectroniques; (iii) apporter des éléments de compréhension à l’origine du développement de contrainte, qui permettent de prédire et contrôler le niveau de contrainte intrinsèque à la croissance de films minces polycristallins.

Download or read book Materials Processing Handbook written by Joanna R. Groza and published by CRC Press. This book was released on 2007-03-28 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of materials science and engineering is rapidly evolving into a science of its own. While traditional literature in this area often concentrates primarily on property and structure, the Materials Processing Handbook provides a much needed examination from the materials processing perspective. This unique focus reflects the changing comple

Download or read book Diffusion Processes in Advanced Technological Materials written by Devendra Gupta and published by Springer Science & Business Media. This book was released on 2013-01-15 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new game book for understanding atoms at play aims to document diffusion processes and various other properties operative in advanced technological materials. Diffusion in functional organic chemicals, polymers, granular materials, complex oxides, metallic glasses, and quasi-crystals among other advanced materials is a highly interactive and synergic phenomenon. A large variety of atomic arrangements are possible. Each arrangement affects the performance of these advanced, polycrystalline multiphase materials used in photonics, MEMS, electronics, and other applications of current and developing interest. This book is written by pioneers in industry and academia for engineers, chemists, and physicists in industry and academia at the forefront of today's challenges in nanotechnology, surface science, materials science, and semiconductors.

Download or read book Handbook of Mechanics of Materials written by Siegfried Schmauder and published by Springer. This book was released on 2019-05-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive reference for the studies of mechanical properties of materials over multiple length and time scales. The topics include nanomechanics, micromechanics, continuum mechanics, mechanical property measurements, and materials design. The handbook employs a consistent and systematic approach offering readers a user friendly reference ideal for frequent consultation. It is appropriate for an audience at of graduate students, faculties, researchers, and professionals in the fields of Materials Science, Mechanical Engineering, Civil Engineering, Engineering Mechanics, and Aerospace Engineering.

Download or read book Thin Film Analysis by X Ray Scattering written by Mario Birkholz and published by John Wiley & Sons. This book was released on 2006-05-12 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions by Paul F. Fewster and Christoph Genzel While X-ray diffraction investigation of powders and polycrystalline matter was at the forefront of materials science in the 1960s and 70s, high-tech applications at the beginning of the 21st century are driven by the materials science of thin films. Very much an interdisciplinary field, chemists, biochemists, materials scientists, physicists and engineers all have a common interest in thin films and their manifold uses and applications. Grain size, porosity, density, preferred orientation and other properties are important to know: whether thin films fulfill their intended function depends crucially on their structure and morphology once a chemical composition has been chosen. Although their backgrounds differ greatly, all the involved specialists a profound understanding of how structural properties may be determined in order to perform their respective tasks in search of new and modern materials, coatings and functions. The author undertakes this in-depth introduction to the field of thin film X-ray characterization in a clear and precise manner.

Download or read book Islands Mounds and Atoms written by Thomas Michely and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crystal growth far from thermodynamic equilibrium is nothing but homoepitaxy - thin film growth on a crystalline substrate of the same material. Because of the absence of misfit effects, homoepitaxy is an ideal playground to study growth kinetics in its pure form. Despite its conceptual simplicity, homoepitaxy gives rise to a wide range of patterns. This book explains the formation of such patterns in terms of elementary atomic processes, using the well-studied Pt/Pt(111) system as a reference point and a large number of Scanning Tunneling Microscopy images for visualization. Topics include surface diffusion, nucleation theory, island shapes, mound formation and coarsening, and layer-by-layer growth. A separate chapter is dedicated to describing the main experimental and theoretical methods.

Download or read book Reactive Sputter Deposition written by Diederik Depla and published by Springer Science & Business Media. This book was released on 2008-06-24 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

Download or read book Thin Films Volume 239 written by E. Arzt and published by Materials Research Society. This book was released on 1992-06-16 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.

Download or read book Thin Films Volume 239 written by W. D. Nix and published by . This book was released on 1992-06-16 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers presented at the 1991 Fall Meeting of the Materials Research Society

Download or read book Residual Stress written by Ismail C. Noyan and published by Springer. This book was released on 2013-03-07 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of Applied Physics written by and published by . This book was released on 2003 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: