Search Results for epitaxy oxide layers

This article describes the Schottky defect and the Frenkel defect in oxides. It provides information on the p-type metal-deficit oxides and n-type semiconductor oxides. The article discusses diffusion mechanisms and laws of diffusion proposed by Fick. It explains the oxide texture of amorphous and epitaxy oxide layers and presents equations for various oxidation reaction rates. The article reviews different theories to describe the oxidation mechanism. These include the Cabrera-Mott, Hauffe-IIschner, Grimley-Trapnell, Uhlig, and Wagner theories.

Gallium-base components can be found in a variety of products ranging from compact disk players to advanced military electronic warfare systems, owing to the factor that it can emit light, has a greater resistance to radiation and operates at faster speeds and higher temperatures. This article discusses the uses of gallium in optoelectronic devices and integrated circuits and applications of gallium. The article discusses the properties and grades of gallium arsenide and also provides information on resources of gallium. The article talks about the recovery techniques, including recovery from bauxite, zinc ore and secondary recovery process and purification. The article briefly describes the fabrication process of gallium arsenide crystals. Furthermore, the article gives a short note on world supply and demand of gallium and concludes with research and development on gallium arsenide integrated circuits.

This article describes the vapor-phase growth techniques applied to the epitaxial deposition of semiconductor films and discusses the fundamental processes involved in metal-organic chemical vapor deposition (MOCVD). It reviews the thermodynamics that determine the driving force behind the overall growth process and the kinetics that define the rates at which the various processes occur. The article provides information on the reactor systems and hardware, MOCVD starting materials, engineering considerations that optimize growth, and the growth parameters for a variety of Group III-V, II-VI, and IV semiconductors.

This article discusses the application of amorphous and crystalline films through plasma-enhanced chemical vapor deposition (PECVD) from the view point of microelectronic device fabrication. It describes the various types of PECVD reactors and deposition techniques. Plasma enhancement of the CVD process is discussed briefly. The article also describes the properties of amorphous and crystalline films deposited by the PECVD process for integrated circuit fabrication.

This article introduces various techniques commonly used in the characterization of semiconductors, namely single-crystal, polycrystalline, amorphous, oxide, organic, and low-dimensional semiconductors and semiconductor devices. The discussion covers material classification, fabrication methods, sample preparation, bulk/elemental characterization methods, microstructural characterization methods, surface characterization methods, and electronic characterization methods.

This article describes eight stages of the atomistic film growth: vaporization of the material, transport of the material to the substrate, condensation and nucleation of the atoms, nuclei growth, interface formation, film growth, changes in structure during the deposition, and postdeposition changes. It also discusses the effects and causes of growth-related properties of films deposited by physical vapor deposition processes, including residual film stress, density, and adhesion.

This article is an overview of the division Surface Analysis of this volume. The division covers various developed surface-analysis techniques, such as scanning probe and atomic force microscopy. The division focuses on the analysis of surface layers that are less than 100 nm. A quick reference summary of surface-analysis methods is presented in this article.

This article examines the characteristics and behavior of scale produced by various types of oxidation. The basic models, concepts, processes, and open questions for high-temperature gaseous corrosion are presented. The article describes the development of geometrically induced growth stresses, transformation stresses, and thermal stresses in oxide scales. It discusses the ways in which stresses can be relieved. The article provides information on catastrophic oxidation, internal oxidation, sulfidation, alloy oxidation, selective oxidation, and concurrent oxidation. It illustrates the relationships between scale morphologies on binary alloys and concludes with a discussion on metal dusting and chlorine corrosion.

Surface modification is the alteration of the surface composition or structure using energy or particle beams. This article discusses two different surface modification methods. The first, ion implantation, is the introduction of ionized species into the substrate using kilovolt to megavolt ion accelerating potentials. The second method, laser processing, is high-power laser melting with or without mixing of materials precoated on the substrate, followed by rapid melt quenching. The article also describes the advantages and disadvantages of the surface modification approach to promote corrosion resistance.

This article discusses the fundamentals of thermal vaporization and condensation and provides information on the various vaporization sources and methods of vacuum deposition. It offers an overview of reactive evaporation and its deposition techniques. The article also explains the advantages, limitations, and applications of vacuum deposition processes. Finally, it provides information on the gas evaporation process, its processing chamber, and related systems.

Coatings and other surface modifications are used for a variety of functional, economic, and aesthetic purposes. Two major applications of thermal spray coatings are for wear resistance and corrosion resistance. This article discusses thermal (surface hardening) and thermochemical (carburizing, nitriding, and boriding) surface modifications, electrochemical treatments (electroplating, and anodizing), chemical treatments (electroless plating, phosphating, and hot dip coating), hardfacing, and thermal spray processes. It provides information on chemical and physical vapor deposition techniques such as conventional CVD, laser-assisted CVD, cathodic arc deposition, molecular beam epitaxy, ion plating, and sputtering.

This article provides a background of the complex relationship between titanium and its alloys with aqueous environments, which is dictated by the presence of a passivating oxide film. It describes the corrosion vulnerability of titanium and titanium oxides by the classification of oxide failure mechanisms. The mechanisms are spatially localized oxide film breakdown by the ingress of aggressive anions; spatially local or homogenous chemical dissolution of the oxide in a strong reducing-acid environment; and mechanical disruptions or depassivation such as scratching, abrading, or fretting. Titanium alloys can be classified into three primary groups such as titanium alloys with hexagonal close-packed crystallographic structure; beta titanium alloys with body-centered cubic crystallographic structures; and alpha + beta titanium alloys including near-alpha and near-beta titanium alloys. The article also illustrates the effects of alloying on active anodic corrosion of titanium and repassivation behavior of titanium and titanium-base alloys.

This article is a brief account of low-energy ion-scattering spectroscopy (LEIS) for determining the atomic structure of solid surfaces. It begins with a description of the general principles of LEIS. This is followed by a section providing information on the equipment used for LEIS. Various steps involved in the sample preparation, calibration, and data analysis are then discussed. The article concludes with a section on the applications and interpretation of LEIS in material analysis, including discussion on surface structural analysis, layer-by-layer (Frank-van der Merwe) growth, and low-energy atom-scattering spectroscopy.

Conventional high-strength aluminum alloys produced via powder metallurgy (P/M) technologies, namely, rapid solidification (RS) and mechanical alloying (mechanical attrition) have high strength at room temperature and elevated temperature. This article focuses on the metallurgy and weldability of dispersion-strengthened aluminum alloys based on the aluminum-iron system that are produced using various RS-P/M processing techniques. It describes weldability issues related to weld solidification behavior, the formation of hydrogen-induced porosity in the weld zone, and the high-temperature deformation behavior of these alloys, which affect the selection and application of fusion and solid-state welding processes. The article provides specific examples of material responses to welding conditions and highlights the microstructural development in the weld zone.

Rutherford backscattering spectrometry (RBS) is a major materials characterization technique that can provide information in a short analysis time. It is used for quantitative compositional analysis of thin films, layered structures, or bulk materials and to measure surface impurities of heavy elements on substrates of lighter elements. This article focuses on RBS and its principles, such as collision kinematics, scattering cross section, and energy loss. It describes the channeling effect and the operation of the RBS equipment. The article also provides information on the applications of RBS.

This article is a detailed account of additive manufacturing (AM) processes for copper and copper alloys such as copper-chromium alloys, GRCop, oxide-dispersion-strengthened copper, copper-nickel alloys, copper-tin alloys, copper-zinc alloys, and copper-base shape memory alloys. The AM processes include binder jetting, ultrasonic additive manufacturing, directed-energy deposition, laser powder-bed fusion, and electron beam powder-bed fusion. The article presents a review of the literature and state of the art for copper alloy AM and features data on AM processes and industrial practices, copper alloys used, selected applications, material properties, and where applicable, compares these data and properties to traditionally processed materials. The data presented and the surrounding discussion focus on bulk metallurgical processing of copper components. The discussion covers the composition and performance criteria for copper alloys that have been reported for AM and discusses key differences in process-structure-property relationships compared to conventionally processed material. The article also provides information on feedstock considerations for copper powder handling.

Low-energy electron diffraction (LEED) is a technique for investigating the crystallography of surfaces and overlayers adsorbed on surfaces. This article provides a brief account of LEED, covering the principles and measurements of diffraction from surfaces. Some of the processes involved in sample preparation are described. In addition, the article discusses the limitations of surface-sensitive electron diffraction and the applications of LEED with examples.

The majority of currently used additive manufacturing (AM) processes are solidification based (SAM). Another class of AM processes consists of those that rely on deformation (DAM) to place material instead of solidification. Although SAM processes are much more widely used, as research and development continues in DAM processes, they are becoming increasingly attractive, especially for the AM of metals. This article discusses some of the more widely used DAM processes, namely ultrasonic additive manufacturing, cold spray process, and friction stir welding, focusing on their applications, advantages, and limitations.

This article presents a general description of pulsed-laser deposition. It describes the components of pulsed-laser deposition equipment. The article also discusses the effects of angular distribution of materials. Finally, the article reviews the characteristics of high-temperature superconductors and ferroelectric materials.

This article provides information on the thermodynamics and kinetics of high-temperature corrosion. The thermodynamics of high-temperature corrosion reactions reveals what reactions are possible under certain conditions and kinetics explains how fast these possible reactions will proceed. The article describes the diffusion process that plays a key role in oxidation and other gaseous reactions with metals. It discusses the development of stress in oxide layers. The article presents the sample preparation methods for high-temperature testing, and expounds the measurement methods of high-temperature degradation. It reviews a number of potential processes, which are responsible for high-temperature corrosion. The article details a wide range of coatings and coating processes for protecting components in a variety of operating conditions. It also discusses the testing methods used for materials at high temperatures, including furnace tests, burner rig testing, and thermogravimetric analysis, and the test methods conducted at high temperature and high pressure.