This document summarizes key aspects of diffusion in solids:
1) Diffusion occurs due to a concentration gradient, which provides a driving force for atoms to move from high to low concentration regions.
2) Diffusion is an important part of materials processing techniques like case hardening and doping of semiconductors.
3) The rate of diffusion depends on factors like temperature, structure, and the diffusion mechanism (e.g. substitutional vs. interstitial). Fick's laws can be used to model and predict diffusion rates.
Non-Gaussian perturbations from mixed inflaton-curvaton scenarioCosmoAIMS Bassett
This document discusses perturbations from a mixed inflaton-curvaton scenario of the early universe. It begins with an overview of perturbations from standard single-field inflation models. It then introduces the curvaton scenario, where a subdominant scalar field called the curvaton produces the primordial density perturbations after inflation ends. The document outlines how the curvaton scenario allows for non-Gaussian perturbations and explores constraints on curvaton-dominated theories. It concludes by discussing including perturbations from both the inflaton and curvaton fields in a mixed scenario.
This document discusses diffusion in solids, including key concepts such as diffusion coefficients, flux, Fick's laws of diffusion, and factors that influence diffusion rates. It provides examples of steady-state and non-steady state diffusion, and how diffusion is used in processes like carburizing steel and doping semiconductors. Temperature is identified as having the most profound effect on diffusion rates, with an exponential relationship between diffusivity and temperature. Higher temperatures and lower activation energies result in faster diffusion.
Ic technology- diffusion and ion implantationkriticka sharma
The document discusses various methods of doping semiconductors, including diffusion and ion implantation. It provides details on Fick's laws of diffusion and their solutions, which describe how dopant concentration changes over time during diffusion. The effects of temperature, electric fields, and oxidation on diffusion are also covered. Ion implantation is introduced as an alternative doping technique that allows for precise control of dopant dose and depth but requires annealing. Key advantages and challenges of each method are highlighted.
This document discusses dopant diffusion, which is the process of introducing controlled amounts of chemical impurities into a semiconductor lattice. Dopant diffusion is used to form source, drain, base, and emitter regions in semiconductor devices. The document covers various diffusion techniques and parameters, including diffusion sources, solid solubility limits, Fick's laws of diffusion, analytical solutions to the diffusion equations, design of diffused layers, and an example design calculation for a boron diffusion process.
Separation of Macromolecules by Their Size: The Mean Span Dimensioncypztm
Size Exclusion Chromatograpphy (SEC, also called GPC) separates polymer molecules by their size in dilute solution, but which size parameter to use has been a matter of debate. This presentation contains a brief summary of our work on this problem.
The document summarizes atmospheric boundary layer activities at ESRL, including research goals, findings, and capabilities. Key points include:
1) ESRL studies the boundary layer using observations from field projects and models to understand processes like pollutant transport, cloud formation, and climate changes.
2) Recent findings relate to mixing depths over water, stable boundary layer structure, and Arctic climate trends driven by boundary layer processes.
3) ESRL capabilities include observations from field projects, chemistry and physics analysis, and models that are used together to advance understanding and prediction of the boundary layer and its interactions.
Hanle Effect Measurements of Spin Lifetime in Zn0.4Cd0.6Se Epilayers Grown on...Oleg Maksimov
This document summarizes a study that used the Hanle effect to measure spin lifetimes in ZnCdSe epilayers grown on InP substrates with varying n-doping levels. Four samples were studied: three Zn0.4Cd0.6Se samples with carrier densities of 8.0×1016 cm-3, 4.3×1017 cm-3, and 1.1×1018 cm-3, as well as an undoped Zn0.5Cd0.5Se sample. Measurements showed that spin lifetime varied non-monotonically with carrier density, reaching a maximum of ~10.5 ns for the sample near the metal-insulator transition.
Specific volume is defined as the inverse of density, or volume per unit mass. Specific weight is defined as the weight or force of a substance per unit volume. Specific gravity or relative density is defined as the ratio of the density of a substance to the density of a standard substance like water at 4°C. The document provides example equations and problems to calculate density, specific volume, specific weight, and specific gravity using mass, volume, and other given values.
Non-Gaussian perturbations from mixed inflaton-curvaton scenarioCosmoAIMS Bassett
This document discusses perturbations from a mixed inflaton-curvaton scenario of the early universe. It begins with an overview of perturbations from standard single-field inflation models. It then introduces the curvaton scenario, where a subdominant scalar field called the curvaton produces the primordial density perturbations after inflation ends. The document outlines how the curvaton scenario allows for non-Gaussian perturbations and explores constraints on curvaton-dominated theories. It concludes by discussing including perturbations from both the inflaton and curvaton fields in a mixed scenario.
This document discusses diffusion in solids, including key concepts such as diffusion coefficients, flux, Fick's laws of diffusion, and factors that influence diffusion rates. It provides examples of steady-state and non-steady state diffusion, and how diffusion is used in processes like carburizing steel and doping semiconductors. Temperature is identified as having the most profound effect on diffusion rates, with an exponential relationship between diffusivity and temperature. Higher temperatures and lower activation energies result in faster diffusion.
Ic technology- diffusion and ion implantationkriticka sharma
The document discusses various methods of doping semiconductors, including diffusion and ion implantation. It provides details on Fick's laws of diffusion and their solutions, which describe how dopant concentration changes over time during diffusion. The effects of temperature, electric fields, and oxidation on diffusion are also covered. Ion implantation is introduced as an alternative doping technique that allows for precise control of dopant dose and depth but requires annealing. Key advantages and challenges of each method are highlighted.
This document discusses dopant diffusion, which is the process of introducing controlled amounts of chemical impurities into a semiconductor lattice. Dopant diffusion is used to form source, drain, base, and emitter regions in semiconductor devices. The document covers various diffusion techniques and parameters, including diffusion sources, solid solubility limits, Fick's laws of diffusion, analytical solutions to the diffusion equations, design of diffused layers, and an example design calculation for a boron diffusion process.
Separation of Macromolecules by Their Size: The Mean Span Dimensioncypztm
Size Exclusion Chromatograpphy (SEC, also called GPC) separates polymer molecules by their size in dilute solution, but which size parameter to use has been a matter of debate. This presentation contains a brief summary of our work on this problem.
The document summarizes atmospheric boundary layer activities at ESRL, including research goals, findings, and capabilities. Key points include:
1) ESRL studies the boundary layer using observations from field projects and models to understand processes like pollutant transport, cloud formation, and climate changes.
2) Recent findings relate to mixing depths over water, stable boundary layer structure, and Arctic climate trends driven by boundary layer processes.
3) ESRL capabilities include observations from field projects, chemistry and physics analysis, and models that are used together to advance understanding and prediction of the boundary layer and its interactions.
Hanle Effect Measurements of Spin Lifetime in Zn0.4Cd0.6Se Epilayers Grown on...Oleg Maksimov
This document summarizes a study that used the Hanle effect to measure spin lifetimes in ZnCdSe epilayers grown on InP substrates with varying n-doping levels. Four samples were studied: three Zn0.4Cd0.6Se samples with carrier densities of 8.0×1016 cm-3, 4.3×1017 cm-3, and 1.1×1018 cm-3, as well as an undoped Zn0.5Cd0.5Se sample. Measurements showed that spin lifetime varied non-monotonically with carrier density, reaching a maximum of ~10.5 ns for the sample near the metal-insulator transition.
Specific volume is defined as the inverse of density, or volume per unit mass. Specific weight is defined as the weight or force of a substance per unit volume. Specific gravity or relative density is defined as the ratio of the density of a substance to the density of a standard substance like water at 4°C. The document provides example equations and problems to calculate density, specific volume, specific weight, and specific gravity using mass, volume, and other given values.
The document discusses a research project on 3D stacked chip architectures and interlayer cooling, including developing through-silicon vias for vertical electrical connections, using two-phase refrigerant cooling to remove heat from chip stacks more effectively than backside cooling, and experimental work on microchannel heat sinks, boiling visualization, and bubble dynamics simulation using an arbitrary Lagrangian-Eulerian technique.
SPATIAL VARIATIONS OF L-BAND EMISSIVITY IN ANTARCTICA, FIRST RESULTS FROM THE...grssieee
The document summarizes initial results from the SMOS satellite mission regarding spatial variations of L-band emissivity in Antarctica. Key findings include:
1) L-band brightness temperature is fairly constant in dry snow zones, suggesting potential to retrieve snow temperature from SMOS data in these areas.
2) Wet snow zones exhibit more temporal brightness temperature variations due to liquid water absorption and formation of icy layers during melt-refreeze cycles.
3) Radiative transfer modeling suggests snowpack density profiles are important for accurately modeling brightness temperature, particularly at horizontal polarization. Further data is needed to refine emissivity estimates and potential snow temperature retrievals from SMOS in dry snow zones.
Atmospheric aberrations in coherent laser systemswtyru1989
The document discusses atmospheric effects on coherent laser systems and compensation methods. It presents:
1) Simulations of atmospheric propagation using phase screens and analyzing phase distortion, beam wander, spreading, and scintillation.
2) Techniques for compensating atmospheric effects in coherent measurements, including phase compensation receivers and adaptive optics.
3) Modeling of beam projection in coherent lidars and analyzing compensation of speckle averaging using non-conjugated adaptive optics.
1) The gamma-ray burst GRB 101225A is explained as being caused by the tidal disruption of a minor body (such as an asteroid or comet) falling onto an isolated neutron star.
2) The light curves and spectra observed across multiple wavelengths are consistent with the predictions of the tidal disruption model.
3) A minor body passing within 105-106 km of a neutron star would be disrupted by the star's tidal forces, with the debris falling back to form an accretion disk around the star and emitting radiation.
study Image and video abstraction by multi scale anisotropic kuwaharaChiamin Hsu
The document describes a multi-scale anisotropic Kuwahara filter for image abstraction and edge-preserving smoothing. It proposes a coarse-to-fine approach using an image pyramid. At each level, it applies an anisotropic Kuwahara filter using locally estimated structure tensors to determine filter shapes, and merges the results with the previous level. This avoids artifacts and overblurring seen in other filters, producing strong abstraction while preserving details in low-contrast regions.
1988 a study of the thermal switching behavior in gd tbfe magneto‐optic films...pmloscholte
1) A study examined the thermal switching behavior of GdTbFe magneto-optic films using two laser beams - a krypton laser (753 nm) to locally heat spots and a semiconductor laser (820 nm) to monitor changes in magnetization.
2) It was observed that magnetization reversal within the heated spots was delayed after the start of heating, with delay times ranging from 200 microseconds to 2 seconds depending on factors like applied field and heating power.
3) Analysis indicated the delayed switching was partly due to the time needed to reach the temperature required for reversal as the spot heated up, though other magnetic processes may also have contributed to the delay.
This document contains 29 multiple choice questions from a 2008 physics exam. The questions cover topics in optics, electronics, atomic and nuclear physics, semiconductors, and electricity and magnetism. For each question, four possible answers are provided and the test-taker must select the single best answer.
An automated and user-friendly optical tweezers for biomolecular investigat...Dr. Pranav Rathi
An automated optical tweezers system was designed and constructed for biomolecular investigations. Key aspects included automation and control of the tweezers, calibration of stiffness and sensitivity, and DNA sample preparation and experiments. Results showed DNA overstretching and unzipping experiments in both water and heavy water. Future work will focus on further automation and investigating DNA-protein interactions.
This document discusses forces on surfaces due to static fluids. It begins by explaining that pressure on a horizontal surface is uniform and can be calculated as force per unit area. An example problem calculates the total force on the bottom of a barrel from oil and water above it. The document then discusses forces on vertical surfaces, noting that pressure varies linearly with depth and is greatest at the bottom, and that average pressure acts at the midpoint. It provides an equation to calculate the total resultant force on an inclined surface from the fluid above it.
1990 crystallization kinetics of thin amorphous in sb filmspmloscholte
1) Evaporated and sputtered InSb films have different crystallization properties. Evaporated films have a lower activation energy of 1.39 eV and crystallize by three-dimensional growth on existing nuclei.
2) Sputtered films have a higher activation energy of 2.7 eV and crystallize by nucleation and subsequent growth on the nuclei. The Avrami exponent indicates sputtered films require crystalline nuclei to form before crystallization can begin.
3) Transmission electron microscopy images show evaporated films have existing nuclei while sputtered films have no visible crystallites in the as-deposited state, requiring nucleation.
Evidence for a black hole remnant in the type iil supernova 1979 cSérgio Sacani
1) The Type IIL supernova SN 1979C has exhibited a remarkably constant X-ray luminosity of (6.5 ± 0.1) × 1038 erg s−1 over 12 years of observations from 1995 to 2007.
2) This steady luminosity is inconsistent with models of a supernova powered by a magnetar or expanding into a dense circumstellar wind, as the luminosity would be expected to decrease over time in these models.
3) The authors propose that the steady X-ray emission provides evidence for accretion onto a stellar-mass (5-10 solar mass) black hole remnant at the center of SN 1979C. Spectral modeling of the X-ray data is consistent with emission from
Building a Strong Financial House 4-29-2011Tim Mooney
The document provides advice on building strong personal finances. It discusses five ways to handle money: earning, spending, saving, giving, and debt. It recommends developing a monthly budget to spend less than you earn, eliminating high-interest debt, and saving 3-6 months of living expenses as an emergency fund. The overall goal is to gain control over cash flow and implement a plan to meet long- and short-term financial objectives.
The document discusses the evolution of radio content in India from pre-independence to the present digital age. It traces the origins and development of radio in India, from amateur stations used by freedom fighters, to the establishment of All India Radio in 1927. It describes how radio was initially used only for political purposes and national integration, but later diversified to include entertainment, commercials, and catering to regional audiences. Modern developments have included the growth of private FM stations since the 1990s, digital technologies like internet radio and podcasts, and more informal and interactive content and communication styles.
Building a Strong Financial House (stand alone)Tim Mooney
How to put the Five Ways to Handle Money into action. Gives a picture of what a steward's financial life actually looks like. Plus, a strategy to get started on handling money faithfully.
This document discusses mechanical properties of materials including:
1. It describes stress, strain, elastic behavior, plastic behavior, toughness, and ductility and how they are measured.
2. It explains different types of stresses including tension, compression, torsion, and shear. It also discusses tensile and shear stress-strain relationships.
3. It covers elastic deformation, plastic deformation, linear elastic properties including Young's modulus, Hooke's law, Poisson's ratio, shear modulus, and bulk modulus. It also discusses yield strength.
Este documento describe un seminario sobre gerencia de sí mismo con el objetivo de proporcionar congruencia personal, laboral y social para generar bienestar emocional. El seminario aborda temas como la crisis de la mitad de la vida, el significado de la adultez, el yo y el sí mismo, a través de enfoques teóricos, introspección y experiencias vivenciales, con el fin de ayudar a las personas a cuestionarse, responsabilizarse y elegir prioridades para su crecimiento personal.
A look at realities about money; the only five ways that a person can handle money; and some action steps toward becoming a faithful steward of finances. Presented to participants in the Support Raising Workshop, Calvary Church, State College, Pennsylvania, on 7-25-2013.
The document discusses a research project on 3D stacked chip architectures and interlayer cooling, including developing through-silicon vias for vertical electrical connections, using two-phase refrigerant cooling to remove heat from chip stacks more effectively than backside cooling, and experimental work on microchannel heat sinks, boiling visualization, and bubble dynamics simulation using an arbitrary Lagrangian-Eulerian technique.
SPATIAL VARIATIONS OF L-BAND EMISSIVITY IN ANTARCTICA, FIRST RESULTS FROM THE...grssieee
The document summarizes initial results from the SMOS satellite mission regarding spatial variations of L-band emissivity in Antarctica. Key findings include:
1) L-band brightness temperature is fairly constant in dry snow zones, suggesting potential to retrieve snow temperature from SMOS data in these areas.
2) Wet snow zones exhibit more temporal brightness temperature variations due to liquid water absorption and formation of icy layers during melt-refreeze cycles.
3) Radiative transfer modeling suggests snowpack density profiles are important for accurately modeling brightness temperature, particularly at horizontal polarization. Further data is needed to refine emissivity estimates and potential snow temperature retrievals from SMOS in dry snow zones.
Atmospheric aberrations in coherent laser systemswtyru1989
The document discusses atmospheric effects on coherent laser systems and compensation methods. It presents:
1) Simulations of atmospheric propagation using phase screens and analyzing phase distortion, beam wander, spreading, and scintillation.
2) Techniques for compensating atmospheric effects in coherent measurements, including phase compensation receivers and adaptive optics.
3) Modeling of beam projection in coherent lidars and analyzing compensation of speckle averaging using non-conjugated adaptive optics.
1) The gamma-ray burst GRB 101225A is explained as being caused by the tidal disruption of a minor body (such as an asteroid or comet) falling onto an isolated neutron star.
2) The light curves and spectra observed across multiple wavelengths are consistent with the predictions of the tidal disruption model.
3) A minor body passing within 105-106 km of a neutron star would be disrupted by the star's tidal forces, with the debris falling back to form an accretion disk around the star and emitting radiation.
study Image and video abstraction by multi scale anisotropic kuwaharaChiamin Hsu
The document describes a multi-scale anisotropic Kuwahara filter for image abstraction and edge-preserving smoothing. It proposes a coarse-to-fine approach using an image pyramid. At each level, it applies an anisotropic Kuwahara filter using locally estimated structure tensors to determine filter shapes, and merges the results with the previous level. This avoids artifacts and overblurring seen in other filters, producing strong abstraction while preserving details in low-contrast regions.
1988 a study of the thermal switching behavior in gd tbfe magneto‐optic films...pmloscholte
1) A study examined the thermal switching behavior of GdTbFe magneto-optic films using two laser beams - a krypton laser (753 nm) to locally heat spots and a semiconductor laser (820 nm) to monitor changes in magnetization.
2) It was observed that magnetization reversal within the heated spots was delayed after the start of heating, with delay times ranging from 200 microseconds to 2 seconds depending on factors like applied field and heating power.
3) Analysis indicated the delayed switching was partly due to the time needed to reach the temperature required for reversal as the spot heated up, though other magnetic processes may also have contributed to the delay.
This document contains 29 multiple choice questions from a 2008 physics exam. The questions cover topics in optics, electronics, atomic and nuclear physics, semiconductors, and electricity and magnetism. For each question, four possible answers are provided and the test-taker must select the single best answer.
An automated and user-friendly optical tweezers for biomolecular investigat...Dr. Pranav Rathi
An automated optical tweezers system was designed and constructed for biomolecular investigations. Key aspects included automation and control of the tweezers, calibration of stiffness and sensitivity, and DNA sample preparation and experiments. Results showed DNA overstretching and unzipping experiments in both water and heavy water. Future work will focus on further automation and investigating DNA-protein interactions.
This document discusses forces on surfaces due to static fluids. It begins by explaining that pressure on a horizontal surface is uniform and can be calculated as force per unit area. An example problem calculates the total force on the bottom of a barrel from oil and water above it. The document then discusses forces on vertical surfaces, noting that pressure varies linearly with depth and is greatest at the bottom, and that average pressure acts at the midpoint. It provides an equation to calculate the total resultant force on an inclined surface from the fluid above it.
1990 crystallization kinetics of thin amorphous in sb filmspmloscholte
1) Evaporated and sputtered InSb films have different crystallization properties. Evaporated films have a lower activation energy of 1.39 eV and crystallize by three-dimensional growth on existing nuclei.
2) Sputtered films have a higher activation energy of 2.7 eV and crystallize by nucleation and subsequent growth on the nuclei. The Avrami exponent indicates sputtered films require crystalline nuclei to form before crystallization can begin.
3) Transmission electron microscopy images show evaporated films have existing nuclei while sputtered films have no visible crystallites in the as-deposited state, requiring nucleation.
Evidence for a black hole remnant in the type iil supernova 1979 cSérgio Sacani
1) The Type IIL supernova SN 1979C has exhibited a remarkably constant X-ray luminosity of (6.5 ± 0.1) × 1038 erg s−1 over 12 years of observations from 1995 to 2007.
2) This steady luminosity is inconsistent with models of a supernova powered by a magnetar or expanding into a dense circumstellar wind, as the luminosity would be expected to decrease over time in these models.
3) The authors propose that the steady X-ray emission provides evidence for accretion onto a stellar-mass (5-10 solar mass) black hole remnant at the center of SN 1979C. Spectral modeling of the X-ray data is consistent with emission from
Building a Strong Financial House 4-29-2011Tim Mooney
The document provides advice on building strong personal finances. It discusses five ways to handle money: earning, spending, saving, giving, and debt. It recommends developing a monthly budget to spend less than you earn, eliminating high-interest debt, and saving 3-6 months of living expenses as an emergency fund. The overall goal is to gain control over cash flow and implement a plan to meet long- and short-term financial objectives.
The document discusses the evolution of radio content in India from pre-independence to the present digital age. It traces the origins and development of radio in India, from amateur stations used by freedom fighters, to the establishment of All India Radio in 1927. It describes how radio was initially used only for political purposes and national integration, but later diversified to include entertainment, commercials, and catering to regional audiences. Modern developments have included the growth of private FM stations since the 1990s, digital technologies like internet radio and podcasts, and more informal and interactive content and communication styles.
Building a Strong Financial House (stand alone)Tim Mooney
How to put the Five Ways to Handle Money into action. Gives a picture of what a steward's financial life actually looks like. Plus, a strategy to get started on handling money faithfully.
This document discusses mechanical properties of materials including:
1. It describes stress, strain, elastic behavior, plastic behavior, toughness, and ductility and how they are measured.
2. It explains different types of stresses including tension, compression, torsion, and shear. It also discusses tensile and shear stress-strain relationships.
3. It covers elastic deformation, plastic deformation, linear elastic properties including Young's modulus, Hooke's law, Poisson's ratio, shear modulus, and bulk modulus. It also discusses yield strength.
Este documento describe un seminario sobre gerencia de sí mismo con el objetivo de proporcionar congruencia personal, laboral y social para generar bienestar emocional. El seminario aborda temas como la crisis de la mitad de la vida, el significado de la adultez, el yo y el sí mismo, a través de enfoques teóricos, introspección y experiencias vivenciales, con el fin de ayudar a las personas a cuestionarse, responsabilizarse y elegir prioridades para su crecimiento personal.
A look at realities about money; the only five ways that a person can handle money; and some action steps toward becoming a faithful steward of finances. Presented to participants in the Support Raising Workshop, Calvary Church, State College, Pennsylvania, on 7-25-2013.
This document is an account statement covering the period from July 1, 2010 to July 31, 2010. It lists transactions including open/close dates and times, types of transactions, instruments, amounts, buy/sell indications, open/close prices, profits/losses, commissions, and other account details. A variety of currency exchange trades were made involving the EUR/USD pair, with opening and closing of positions at different price points over the period.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document summarizes key concepts about crystal structures of metals and ceramics. It discusses how atoms assemble into solid structures, and how metallic and ceramic structures differ. Metallic structures tend to be densely packed with spherical atoms, while ceramic structures involve directional ionic or covalent bonding between atoms of different sizes. Common metallic structures include body-centered cubic, face-centered cubic, and hexagonal close-packed arrangements.
This document discusses crafting an effective brand positioning strategy. It explains that positioning is defining a brand's place in the consumer's mind relative to competitors based on important attributes. Choosing the right positioning involves deciding where to place the brand, analyzing competitors, developing a value proposition, and defining points of parity and points of difference. An effective positioning strategy differentiates the brand in a way that is important, distinctive, superior, communicable, preemptive, affordable, and profitable for the company.
These diagrams are useful for assessing ceramic performance at high temperatures. Phase diagrams have been experimentally determined for many ceramic systems, often involving oxides sharing a common element like oxygen. The document then summarizes several important ceramic systems, including their phase diagrams and key phases present. It discusses how mechanical properties like strength and fracture behavior are limited in ceramics, and outlines factors like microcracks, flaws, and grain boundaries that contribute to their brittle fracture. Various deformation and strengthening mechanisms in crystalline and non-crystalline ceramics are also summarized.
Diffusion is the mass transport of atoms in solids by atomic motion. There are two main mechanisms: vacancy diffusion, where atoms exchange with vacancies in the lattice, and interstitial diffusion, where smaller atoms diffuse between lattice sites. The rate of diffusion depends on factors like temperature, activation energy, and the concentration gradient. Fick's laws can be used to calculate the flux of diffusing atoms and model diffusion processes. Controlling diffusion is important for applications like alloy processing and semiconductor doping.
This document discusses diffusion in solids, including key questions about how diffusion occurs and how to predict diffusion rates. It describes experiments demonstrating diffusion and simulations showing diffusion mechanisms. Diffusion depends on factors like temperature, structure, and vacancy concentration. Processes like alloying and semiconductor doping use diffusion, and diffusion models use concepts like flux and concentration profiles.
This document discusses diffusion in solids and provides examples to illustrate key concepts. It begins by outlining issues to address, such as how diffusion occurs and how the rate depends on structure and temperature. Experimental demonstrations of diffusion are described, including using a glass tube filled with ink and water to measure diffusion distance over time. Mechanisms of diffusion like substitutional and interstitial diffusion are explained. Examples of processing using diffusion include case hardening of gears and doping semiconductors. Fick's laws of diffusion are outlined to model concentration profiles and flux. Factors affecting diffusion rates like temperature, crystal structure, and atom size are summarized.
This summary provides the key information from the document in 3 sentences:
The document discusses diffusion, including how it occurs, why it is an important process, how the rate of diffusion can be predicted, and how it depends on structure and temperature. Different diffusion mechanisms like vacancy diffusion, interstitial diffusion, and self-diffusion are described. Examples of diffusion applications in areas like case hardening, semiconductor doping, and chemical protective clothing are presented to illustrate how diffusion is used in processing.
Interdiffusion, reactions, and transformations in thin filmMd Ataul Mamun
This document discusses various topics related to interdiffusion, reactions, and transformations in thin films:
1. It explains the concepts of diffusion, nucleation and grain growth that can occur in thin films. Diffusion is impacted by factors like temperature, grain boundaries, and dislocations.
2. Interdiffusion in thin films occurs much faster than in bulk materials due to diffusion along grain boundaries and dislocations. This can impact thin film integrity over time.
3. Reaction and compound formation at interfaces between thin films is discussed, like the growth of SiO2 at the Si/O2 interface or intermetallic compound formation.
4. Phase transformations and the use of diffusion barriers to prevent undesirable
Diffusion is the mass transport of atoms through a solid by atomic motion. There are two main mechanisms: vacancy diffusion, where atoms exchange with vacancies in the lattice, and interstitial diffusion, where smaller atoms diffuse through spaces in the lattice. The rate of diffusion increases exponentially with temperature according to an Arrhenius relationship and is quantified by Fick's laws of diffusion. Diffusion plays an important role in many materials processes and semiconductor device fabrication.
The document discusses adsorption equilibria and regeneration. It defines adsorption as the accumulation of matter at the interface between two phases, such as a gas and a solid surface. The document then describes different types of adsorption including physical adsorption, chemical adsorption, and ion exchange. Common adsorption isotherm models are also summarized, such as the Langmuir, Freundlich, BET, and Temkin isotherms. Finally, five types of physisorption isotherms are described that can occur on solid surfaces depending on the material properties.
There are three main mechanisms of heat transfer: conduction, convection, and radiation. Conduction involves the direct contact and transfer of kinetic energy between molecules. The rate of conductive heat transfer depends on the temperature gradient, surface area of contact, and the material's thermal conductivity. Materials with high thermal conductivity like metals are good conductors, while still air and materials that trap air are good insulators. Thermal resistance can be used to calculate the rate of heat transfer through multiple conducting layers.
There are three main mechanisms of heat transfer: conduction, convection, and radiation. Conduction involves the direct contact and transfer of kinetic energy between molecules. The rate of conductive heat transfer depends on the temperature gradient, surface area of contact, and the material's thermal conductivity. Materials with high thermal conductivity like metals are good conductors, while still air and materials that trap air are good insulators. Thermal resistance can be used to calculate the rate of heat transfer through multiple conducting layers.
This document summarizes the key findings from fitting experimental data on radiation-induced absorption in optical fibers to fractal kinetic models. The models provide better fits than classical kinetic solutions, with fitting parameters suggesting a transition from classical to fractal behavior at lower dose rates. Specifically:
1) Fractal kinetic models with stretched exponential solutions provided excellent fits to the data over four orders of magnitude in dose rate.
2) Parameters like the rate coefficient and saturation value varied with dose rate as predicted by the fractal models, indicating a transition from classical to fractal kinetics.
3) Including additional defect populations improved fits and supported the fractal kinetics interpretation of the data.
This tutorial covers heat transfer via convection and radiation. It discusses:
- Natural and forced convection, and how to calculate heat transfer rates using surface heat transfer coefficients.
- Combining conduction and convection to solve problems involving multi-layer surfaces.
- The basic theory of radiated heat transfer, and how emissivity and surface shape affect heat transfer rates.
- Calculating effective surface heat transfer coefficients to model radiation using similar equations as convection.
- Worked examples are provided to demonstrate calculating heat transfer rates via combined conduction, convection and radiation in practical scenarios.
A comparison of VLSI interconnect modelshappybhatia
This document presents a comparative study of delay analysis for carbon nanotube and copper based VLSI interconnect models. It outlines the introduction, interconnect models, factors affecting interconnect performance, and comparison of CNT vs copper. It then discusses analytical delay estimation using the driver interconnect model and modified nodal analysis, as well as SPICE simulation results comparing CNT and copper. The goal is to analyze and compare the delay performance of CNT and copper interconnects.
A Comparison Of Vlsi Interconnect Modelshappybhatia
The document presents a comparative study of delay analysis for carbon nanotube and copper based VLSI interconnect models. It analyzes the performance of CNT and copper interconnects using analytical delay estimation techniques like the driver interconnect load model, modified nodal analysis, and the unified time delay model. Simulation results show that CNT bundle interconnects provide significant delay improvement over copper interconnects for certain parameters like repeater sizing and pitch ratio.
This document is the front cover of a physics exam from the University of Cambridge International Examinations. It provides instructions for a multiple choice exam with 40 questions on physics. The exam covers topics such as mechanics, materials, waves, electricity, quantum and nuclear physics, thermodynamics, and astronomy. Candidates are instructed to choose the correct answer for each question and record their choice on an answer sheet provided. They are given 1 hour to complete the exam.
The document discusses heat conduction equations. It begins by stating the learning objectives, which are to explain heat transfer concepts and solve one-dimensional heat conduction problems. It then derives the general heat conduction equation for one-dimensional conduction in a plane wall or long cylinder. The equation relates the temperature gradient to heat generation and transient effects using variables like thermal conductivity, density and heat capacity.
Here are the steps to solve this problem:
1. Calculate the radiative heat loss from the absorber:
Qrad = εσA(Ts4 - Tsky4) = 0.1×5.67×10-8×(120+273)4 - (-10+273)4 = 33 W/m2
2. Calculate the convective heat loss:
h = 0.22(Ts - T∞)1/3 = 0.22(120-30)1/3 = 5.1 W/m2K
Qconv = hA(Ts - T∞) = 5.1×(120-30) = 51 W/m2
Diffusion rates can be orders of magnitude faster along interfaces like grain boundaries and dislocations compared to bulk crystals. This is due to faster diffusion occurring in a thin slab near the interface that contains disordered material. Diffusion in solids with interfaces can be modeled by replacing interfaces with thin slabs possessing much higher diffusivities. Self-diffusion data follows the trend that diffusion is fastest at free surfaces and slowest in the bulk lattice.
This document discusses heat transfer, including:
1. The three modes of heat transfer - conduction, convection, and radiation. It provides equations to calculate heat transfer via these modes.
2. Key heat transfer concepts like thermal conductivity, convection coefficients, emissivity, and overall heat transfer coefficients.
3. Examples of calculating heat transfer through composite walls and heat exchanger surfaces.
This chapter discusses diffusion in solids, including:
1) How diffusion occurs via vacancy or interstitial mechanisms and depends on structure and temperature.
2) Fick's laws of diffusion and how diffusion can be quantified by measuring flux.
3) Examples of diffusion applications like case hardening and doping semiconductors.
4) How the diffusion coefficient increases exponentially with temperature and can be used to solve problems involving steady-state and non-steady-state diffusion.
The document discusses diffusion in materials, including:
1) Diffusion occurs via atomic mechanisms like vacancy and interstitial diffusion, moving atoms from high to low concentration areas.
2) Examples of diffusion applications are case hardening of gears and doping of semiconductors.
3) Fick's first law describes steady-state diffusion as flux proportional to the concentration gradient, via the diffusion coefficient D.
1. Chapter 6
DIFFUSION IN SOLIDS
• How does diffusion occur?
• Why is it an important part of processing?
• How can the rate of diffusion be predicted for
some simple cases?
• How does diffusion depend on structure
and temperature?
2. Driving force for movement
In general, force is a position derivative of energy (F = - dE/dr).
In other words, if there is any energy difference in space,
there is a force which will act on matters - Force will move things.
(ex1) Potential energy by gravity:
Apple falls from high altitude (high potential energy) to
low altitude (low potential energy).
(ex2) Drift current by battery (electrical potential energy).
(ex3) Atoms move from high concentration (high chemical potential)
to low concentration (low chemical potential) → Diffusion!
* Concentration gradient is the driving force.
(well, it is chemical potential energy to be precise.
Concentration gradient is not sufficient condition for diffusion.)
3. Interdiffusion
• Interdiffusion: In an alloy, atoms tend to migrate
from regions of large concentration.
Initially After some time
Cu Ni
100% 100%
0 0
Concentration Profiles Concentration Profiles
4. DIFFUSION MECHANISMS
Substitutional diffusion and interstitial diffusion
(1) Substitutional (Vacancy) Diffusion:
• applies to substitutional impurities
• atoms exchange with vacancies
• rate depends on:
--number of vacancies
--activation energy to exchange.
increasing elapsed time
5. Vacancy Diffusion
• Simulation of
interdiffusion
across an interface:
• Rate of substitutional
diffusion depends on:
--vacancy concentration
--frequency of jumping.
Temperature dependent.
6. (2) Interstitial Diffusion
tetrahedral octahedral
• Applies to interstitial
(small) impurities FCC
(O, N, C, etc).
• More rapid than vacancy
diffusion
BCC
Why?
7. Self-Diffusion
• Self-diffusion: In an elemental solid, atoms also migrate
through diffusion. Driving force can be
described by more general thermodynamic
potential. This type of diffusion in the
crystalline material generally occurs
through substitutional diffusion.
Label some atoms After some time
C
C
A D
A
D
B
B
8. PROCESSING USING DIFFUSION (1)
• Case Hardening:
--Diffuse carbon atoms
into the host iron atoms
at the surface.
--Example of interstitial
diffusion is a case
hardened gear.
• Result: The "Case" is
-- hard to deform: C atoms
"lock" planes from shearing.
-- hard to crack: C atoms put
the surface in compression.
9. PROCESSING USING DIFFUSION (2)
• Doping Silicon with P for n-type semiconductors:
• Process:
0.5mm
1. Deposit P rich
layers on surface.
magnified image of a computer chip
silicon
2. Heat it.
3. Result: Doped
light regions: Si atoms
semiconductor
regions.
light regions: Al atoms
silicon
10. MODELING DIFFUSION: FLUX
• Flux: Amount of matter that passes
through unit area per unit time.
1 dM kg atoms
J= ⇒ 2 or 2
A dt m s m s
• Flux can be measured for:
--vacancies x-direction
--host (A) atoms
--impurity (B) atoms
• Flux is directional Quantity. Unit area A
y J through
y
which
Jx atoms
Jz move.
x
z
11. MODELING DIFFUSION: FLUX
• Flux can be also given by
Flux = (conductivity) x (driving force)
(ex) Electrical current (I) = (1/R) x V (Ohm’s law)
- For diffusion, the conductivity is called
‘diffusivity’ or ‘diffusion coefficient’,
and it is typically presented by the symbol, D.
- Driving force is concentration gradient, ∆C/∆x.
- One important issue when you face with the diffusion problem
is whether or not things change as a function of time.
Steady state diffusion (nothing changes.)
Non steady-state diffusion (flux & conc. profile change.)
12. STEADY STATE DIFFUSION
(Fick’s First Law)
• Steady State:
Steady State:
Jx(left) Jx(right) J x(left) = Jx(right)
x
Concentration, C, in the box doesn’t change w/time.
dC
• Apply Fick's First Law: J x = −D
dx
dC dC
• If Jx)left = Jx)right , then =
dx left dx right
• Result: the slope, dC/dx, must be constant
(i.e., slope doesn't vary with position and time)!
13. EX: STEADY STATE DIFFUSION
3
g/m
• Steel plate at . 2k 3
=1 g/m
700C with C1 .8k
=0
C2
geometry Carbon Steady State =
rich straight line!
shown:
gas Carbon
deficient
gas
D=3x10-11m2/s
0 x1 x2
10
• Q: How much 5m
m
m
m
carbon transfers
from the rich to C2 − C1 = −9 kg
J = −D 2.4 × 10
the deficient side? x2 − x1 m2s
14. DIFFUSION AND TEMPERATURE
• Diffusivity increases with T.
pre-exponential [m2/s] (see Table 5.2, Callister 6e)
activation energy
Q [J/mol],[eV/mol]
diffusivity D = Do exp − d (see Table 5.2, Callister 6e )
RT
gas constant [8.31J/mol-K]
• Experimental Data:
1500
1000
600
300
T(C)
10-8 D has exp. dependence on T
C
in
D (m2/s) Ci Recall: Vacancy does also!
γ-
nα
Fe
-Fe Dinterstitial >> Dsubstitutional
10-14 C in α-Fe Cu in Cu
Zn
Al in Al
Fe
C in γ-Fe
in Cun α-
Al
Fe in α-Fe
Cu in Fe
Fe -Fe
in
in
Fe in γ-Fe
Al
γ
i
Zn in Cu
Cu
10-20
0.5 1.0 1.5 2.0 1000K/T
15.
16. NON STEADY STATE DIFFUSION
(Fick’s Second Law)
dx
• Concentration profile,
J(left) J(right)
C(x), changes
w/ time. Concentration,
C, in the box
• To conserve matter: • Fick's First Law:
J(right) − J(left) = dC dC
− J = −D or
dx dt dx
dJ = dC dJ = d2 C (if D does
− −D not vary
dx dt dx dx2 with x)
(Temperature
equate is fixed here.)
• Governing Eqn.:
dC d2C
=D 2 Fick’s Second Law
dt dx
17. NON STEADY STATE DIFFUSION
• Copper diffuses into a bar of aluminum.
Surface conc.,
Cs of Cu atoms Al bar
pre-existing conc., C o of copper atoms
C(x,t)
Cs Boundary condition:
t=0, C=C0 at 0≤x ≤∞
t
t2 3
t>0, C=Cs at x=0
to t1
C=C0 at x=∞
Co
x=0 position, x
• General solution
for C(x,t): C(x, t) − Co = x
1 − erf
2 Dt
Fick’s 2nd law is Cs − Co
the differential equation. "error function"
18. NON STEADY STATE DIFFUSION
(ex1) – EXAMPLE PROBLEM 6.2 (page 162)
Carburizing steel with methane gas (source for C)
Q. How long will it take to achieve a carbon content of 0.80 wt%
at a position 0.5mm below the surface of the steel piece under
given Cs and Co condition?
A. The question gave you C(x,t) and x. Need to find t.
C(x, t) − Co = x
1 − erf
2 Dt
Cs − Co
"error function"
z
19. PROCESSING QUESTION
• Copper diffuses into a bar of aluminum.
• 10 hours at 600C gives desired C(x).
• How many hours would it take to get the same C(x)
if we processed at 500C?
Key point 1: C(x,t500C) = C(x,t600C).
Key point 2: Both cases have the same Co and Cs.
• Result: Dt should be held constant.
C(x,t) − Co x
= 1 − erf
2Dt
(Dt)500ºC =(Dt)600ºC
Cs − Co
5.3x10-13m2/s 10hrs
(Dt)600 Note: values
• Answer: t 500 = = 110 hr of D are
-14m2/s
D500 provided here.
4.8x10