bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring Motions of MEMS
Authors: Freeman Dennis M.
Published: February 2011

Testing microelectromechanical systems (MEMS) includes testing a variety of electrical and mechanical signals. While powerful tools are available to test the electrical behavior of microfabricated systems, relatively few tools are available to measure micromechanical behavior.
High-Aspect-Ratio Structures for MEMS
Authors: Pang Stella W.
Published: February 2011

Many microelectromechanical systems (MEMS) use the changing capacitance of movable parallel plates to drive and sense motion. An increase in this capacitance improves the performance of these micromechanical structures by means of increased electromechanical coupling for lower driving voltages and increased sensitivity of the micromechanical motion.
Diamond and Amorphous Carbon MEMS
Authors: Sullivan J.P. , Friedmann T.A. , Hjort K.
Published: February 2011

The designer of microelectromechanical systems (MEMS) can increase MEMS performance either by improved mechanical design or by the selection of a MEMS material with improved mechanical performance. In the quest to identify highperformance MEMS materials, diamond and amorphous carbon have recently emerged as a promising class of materials.
A “Silicon Eye” Using Mems Micromirrors
Authors: Clark Natalie
Published: February 2011

The U.S. Air Force Research Laboratory's (AFRL) aggressive pursuit of reducing the size and weight of satellite systems for advanced space missions is providing a vital thrust to the development of “systemson-a-chip.” Adaptive optics technologies offer tremendous potential in reducing the weight and cost of space-based optical systems.
The DMDTM Projection Display Chip: A MEMS-Based Technology
Authors: Hornbeck Larry J.
Published: February 2011

The possibility of an all-digital (sourceto-eye) projection display was realized in 1987 with the invention of the Digital Micromirror Device™ projection display chip at Texas Instruments (TI). The DMD™ chip is a microelectromechanical systems (MEMS) array of fast digital micromirrors, monolithically integrated onto and controlled by an underlying silicon memory chip. Digital Light Processing™ projection displays are based on the DMD chip. DLP™ projection displays present bright, seamless images to the eye that have high image fidelity, and stability.
Micromachining for rf Communications
Authors: Young Darrin J.
Published: February 2011

The increasing demand for wireless communication applications, such as cellular and cordless telephones, wireless data networks, and global positioning systems, motivates a growing interest in building miniature radio transceivers that can support multistandard capabilities. Such transceivers will greatly enhance the convenience and accessibility of various wireless services.
Microsystems for Chemical and Biological Applications
Authors: Lindner Duane
Published: February 2011

Over the past decade, there has been an explosive growth in efforts directed at developing and utilizing an array of novel microsystems in important applications in chemistry and biology. In parallel, the commercial potential of these applications has fueled the creation of hundreds of new companies and the expansion of research and development efforts at established commercial organizations. In this article, we outline the spectrum of applications of these systems and highlight some of the materials and fabrication challenges that they present.
Hybrid Organic–Inorganic Materials
Authors: Loy Douglas A.
Published: February 2011

This issue of MRS Bulletin focuses on the preparation and application of hybrid organic–inorganic materials, which are broadly defined as synthetic materials with organic and inorganic components. Hybrid organic–inorganic materials are of two kinds: homogeneous systems derived from monomers or miscible organic and inorganic components, and heterogeneous and phase-separated systems with domains ranging from angstroms to micrometers in size.
Process Monitoring of Fiber-Reinforced Polymer Composites
Authors: Degamber B. , Fernando G. F.
Published: February 2011

This article presents a review of optical-fiber-based process-monitoring techniques that can be used to track the chemical reactions that take place during the processing of materials, with specific reference to thermosetting resins. The techniques covered include quantitative process-monitoring methods based on near and mid-infrared, Raman, UV–visible, evanescent wave, and fluorescence spectroscopy. The basis for refractive-index-based process monitoring using optical fibers is also presented. The techniques described here can be readily applied to other classes of materials and other areas of interest such as aging and degradation. Recent advances in noncontact process monitoring are also presented.
Electroactive Organic Materials
Authors: Bao Zhenan , Bulovic Vladimir , Holmes Andrew B.
Published: February 2011

This brief article describes the content of the June 2002 issue of MRS Bulletin focusing on Electroactive Organic Materials. These materials are now being considered as the active components in displays, electronic circuits, solar cells, chemical and biological sensors, actuators, lasers, memory elements, and fuel cells. The flexibility of their molecular design and synthesis makes it possible to fine-tune the physical properties and material structure of organic solids to meet the requirements of technologically significant applications. In contrast to inorganic materials, active organic thin films can be deposited at much lower substrate temperatures (less than 120°C) in low-vacuum or atmospheric-pressure environments. It has been demonstrated that low-cost deposition techniques such as solution spin-coating, casting, and even printing can be used for the deposition of solution-soluble organic materials. These processing advantages, together with the natural abundance of organic solids, make electroactive organic materials attractive for large-area and low-cost applications.
Recent Developments in Light-Emitting Polymers
Authors: Rees Ian D. , Robinson Kay L. , Holmes Andrew B. , Towns Carl R. , O'Dell Richard
Published: February 2011

Conjugated light-emitting polymers (LEPs) have real potential to serve as the active layer in a new generation of emissive displays. Emerging as lead candidates for first-generation displays are poly(1,4-phenylene vinylene)s (PPVs) and poly(9,9-dialkylfluorene)s, as well as other polyaromatic materials. The poly(fluorene)s are at present the most commercially developed of these LEP materials for red–green–blue (RGB) applications. The low power consumption of LEP devices in general makes them particularly suited to mobile applications. Combining solution-processable emissive polymers with direct-patterning methods such as ink-jet printing will lead to the possibility of low-cost, high-resolution displays. The synthesis and properties of PPVs and poly(9,9-dialkylfluorene)s are briefly reviewed in this article, with a major focus on recent developments.
Semiconducting Block Copolymers for Self-Assembled Photovoltaic Devices
Authors: Hadziioannou Georges
Published: February 2011

This article focuses on self-assembled photovoltaic materials based on a new class of semiconducting block copolymers for application in photovoltaic devices. Topics discussed include the materials concept for efficient photovoltaic-device structures, their macromolecular design and synthesis, and their performance in relation to their molecular, mesoscopic, and interfacial structures. An ideal organic material for this application would have to compete with amorphous silicon in regard to energy-conversion efficiency and fabrication costs. The potential of the semiconducting block copolymers presented in this review lies in the promise of large-area, mechanically flexible, self-structured photovoltaic devices fabricated by inexpensive processing techniques.
Conjugated-Polymer Micro- and Milliactuators for Biological Applications
Authors: Immerstrand C. , Holmgren-Peterson K. , Magnusson K.-E. , Jager E. , Krogh M. , Skoglund M. , Selbing A. , Inganäs O.
Published: February 2011

The development of new conjugated-polymer tools for the study of the biological realm, and for use in a clinical setting, is reviewed in this article. Conjugated-polymer actuators, based on the changes of volume of the active conjugated polymer during redox transformation, can be used in electrolytes employed in cell-culture media and in biological fluids such as blood, plasma, and urine. Actuators ranging in size from 10 μm to 100 μm suitable for building structures to manipulate single cells are produced with photolithographic techniques. Larger actuators may be used for the manipulation of blood vessels and biological tissue.
Blue and Near-Ultraviolet Vertical-Cavity Surface-Emitting Lasers
Authors: Nurmikko Arto , Han Jung
Published: February 2011

Vertical-cavity surface-emitting lasers (VCSELs) based on gallium nitride semiconductor heterostructures represent a contemporary focus of research, the aim of which is to develop a new class of planar microdevices in the blue, violet, and near-ultraviolet ranges. We review recent progress in this exploratory area, to highlight the challenges and scientific excitement associated with the efforts that are under way to create flexible, short-wavelength sources for applications expected to range from biomedical diagnostics to solid-state displays and lighting.
Vertical-Cavity Surface-Emitting Lasers: Light for the Information Age
Authors: Choquette Kent D.
Published: February 2011

The emergence of miniature light sources such as the vertical-cavity surface-emitting laser (VCSEL) is poised to advance the information age. The development of VCSELs has stimulated a wide range of materials research into epitaxial growth and device-fabrication technologies. In this article, current and emerging applications that are guiding the commercial development of VCSELs are first considered, followed by discussions of the VCSEL epitaxial structure and fabrication technologies. This brief overview will also mention recent efforts aimed at achieving long-wavelength VCSELs grown on GaAs substrates, as well as approaches for achieving a high modulation rate.
Infrared Vertical-Cavity Surface-Emitting Lasers: An Industrial Perspective
Authors: Kisker David W. , Bisberg Jeff E.
Published: February 2011

Optical components based on vertical-cavity surface-emitting lasers (VCSELs) are moving from 850-nm wavelengths to 1.31-μm and 1.55-μm wavelengths. These long-wavelength devices, enabled by new developments in materials technology, will compete directly with distributed-feedback (DFB) and Fabry-Pérot (FP) laser technologies in fiber-optic markets. In addition, the unique properties of VCSELs are opening up a new category of optically integrated components that are not possible with traditional edge-emitting laser source technologies. These VCSEL structures, such as linear and two-dimensional arrays, have the potential to dramatically reduce the cost structure of traditional optical networking equipment and provide a path for rapid growth in optical bandwidth.
Dislocation Plasticity in Thin Metal Films
Authors: Kraft O. , Freund L. B. , Phillips R. , Arzt E.
Published: February 2011

This article describes the current level of understanding of dislocation plasticity in thin films and small structures in which the film or structure dimension plays an important role. Experimental observations of the deformation behavior of thin films, including mechanical testing as well as electron microscopy studies, will be discussed in light of theoretical models and dislocation simulations. In particular, the potential of applying strain-gradient plasticity theory to thin-film deformation is discussed. Although the results of all studies presented follow a “smaller is stronger” trend, a clear functional dependence has not yet been established.
Distributed Bragg Reflectors for Vertical-Cavity Surface-Emitting Lasers
Authors: Breiland W.G. , Allerman A.A. , Klem J.F. , Waldrip K.E.
Published: February 2011

Distributed Bragg reflectors (DBRs) not only serve as high-reflectance mirrors to define the laser cavity of a vertical-cavity surface-emitting laser (VCSEL), but they also must conduct electricity, confine currents, and provide a single-crystal template for the gain region of the laser. Basic optical and electrical properties of DBRs are presented in this article. Three examples of DBR structures used in VCSEL applications from the ultraviolet to the infrared are given to illustrate the complexity and range of materials science issues that are encountered in DBR growth. Fabrication issues are also discussed.
Mechanisms Active during Fracture under Constraint
Authors: Cook Robert F. , Suo Z.
Published: February 2011

Many advanced technologies center on devices of small feature sizes made of diverse materials. Internal stresses that arise in the devices during fabrication and use can result in fracture. Fracture of an individual feature in such a device may impair the function of the device. The materials surrounding the feature have a constraining effect on the elastic energy available to drive the fracture, the plastic flow associated with the fracture, and sometimes even the atomic processes at the crack tip. This article reviews fracture behavior in small structures, several distinct roles played by plasticity, and bond-breaking kinetics. Research challenges are alsooutlined.
Lithium Batteries for Biomedical Applications
Authors: Takeuchi Esther S. , Leising Randolph A.
Published: February 2011

Lithium batteries have been successfully used in implantable biomedical devices for the last 30 years, and in some cases the use of lithium power sources has significantly contributed to the viability of the device. These battery systems fall into two major categories: primary, or single-use, cells containing lithium-metal anodes; and secondary, or rechargeable, systems utilizing lithium-ion chemistry. Primary lithium batteries have been used for implantable devices such as cardiac pacemakers, drug pumps, neurostimulators, and cardiac defibrillators. Rechargeable batteries have been used with left ventricular assist devices and total artificial hearts. All of these cells share the characteristics of high safety, reliability, energy density, and predictability of performance. Additionally, state-of-charge indication and low self-discharge are important features, along with charging safety and high cycle life for rechargeable cells.
Mechanical Properties in Small Dimensions: Comments from Industry
Authors: Vinci Richard P. , Baker Shefford P.
Published: February 2011

The following are commentaries provided by representatives from industry. These short articles lend an additional context in which to appreciate the importance of the issues and mechanisms discussed in the technical articles. The authors of the commentaries point out that the basic principles that underlie the influence of scale on material behavior are not only interesting in their own right, but also are directly applicable to issues of great significance to designers and manufacturers of small-scale devices and structures. In addition, directions for future emphasis are suggested.
Issues in Energy Storage for Electric-Based Transportation
Authors: Nazri Gholam-Abbas
Published: February 2011

The key to market success for electric vehicles (EVs) has always been the energy-storage device, which limits driving range and vehicle acceleration. In many respects, rechargeable lithium batteries are the most attractive technology for storing energy and delivering it on demand in an automobile. Past and ongoing efforts to develop electric-based automotive propulsion systems are chronicled in this article.
Up Close: Materials Research Science and Engineering Centers—U.S. National Network for Materials Research
Authors: Briant Clyde L.
Published: February 2011

In 1994, the U.S. National Science Foundation (NSF) established Materials Research Science and Engineering Centers (MRSECs). The goal was to provide support for interdisciplinary materials research and education of the highest quality while addressing fundamental problems in science and engineering that are important to society. The centers are expected to undertake materials research of a scope and complexity that would not be feasible under traditional funding for individual research projects or small groups. Centers are funded for a limited period of time—currently five years—after which they can re-compete against new proposals. In 1994, MRSECs were established at 11 universities throughout the country. Two years later, 13 new centers were established in a second round of funding. Additional competitions were completed in 1998, 2000, and 2002. As of April 2002, there were 29 MRSECs.
Organic Materials Science
Authors: Whitesides George M.
Published: February 2011

The following article is based on the presentation given by George M. Whitesides, recipient of the 2000 MRS Von Hippel Award, the Materials Research Society's highest honor, at the 2000 MRS Fall Meeting in Boston on November 29, 2000. Whitesides was cited for “bringing fundamental concepts of organic chemistry and biology into materials science and engineering, through his pioneering research on surface modification, self-assembly, and soft lithography.” The article focuses on the growing role of organic chemistry in materials science. Historically, that role has been to provide organic polymers for use in structures, films, fibers, coatings, and so on. Organic chemistry is now emerging as a crucial part of three new areas in materials science. First, it provides materials with complex functionality. Second, it is the bridge between materials science and biology/medicine. Building an interface between biological systems and electronic or optical systems requires close attention to the molecular level of that interface. Third, organic chemistry provides a sophisticated synthetic entry into nanomaterials. Organic molecules are, in fact, exquisitely fabricated nanostructures, assembled with precision on the level of individual atoms. Colloids are a related set of nanostructures, and organic chemistry contributes importantly to their preparation as well.
Metallic Hydrides II: Materials for Electrochemical Storage
Authors: Joubert J.-M. , Latroche M. , Percheron-Guégan A.
Published: February 2011

For a century, nickel-cadmium (Ni-Cd) batteries have been widely used as electrochemical energy-storage cells. However, due to the rapid development of portable electronic devices and the increasing search for cleaner electric vehicles, new generations of batteries have been investigated during the last few decades. Among them, nickel metal hydride (Ni-MH) batteries, with their larger capacities and improved environmental compatibility, have shown their ability to replace Ni-Cd cells. The negative electrodes of Ni-MH batteries are made of reversibly hydride-forming intermetallic compounds. In this article, the crystallographic and thermodynamic properties of these compounds will be reviewed. Their hydrogen-absorption properties, their electrochemical performance, and the solutions that have been found to achieve reliable cycle life will be presented. The industrial market for Ni-MH batteries will also be discussed in comparison with other battery systems.
Metallic Hydrides III: Body-Centered-Cubic Solid-Solution Alloys
Authors: Akiba E. , Okada M.
Published: February 2011

Hydrogen-absorbing alloys with bcc (body-centered-cubic) structures, such as Ti-V-Mn, Ti-V-Cr, Ti-V-Cr-Mn, and Ti-Cr-(Mo, Ru), have been developed since 1993. These alloys have a higher hydrogen capacity (about 3.0 mass%) than conventional intermetallic hydrogen-absorbing alloys. Generally, bcc metals and alloys exhibit two plateaus in pressure–composition isotherms, but the lower plateau is far below atmospheric pressure at room temperature. Many efforts have been made to increase hydrogen capacity and raise the equilibrium pressure of this lower plateau. The crystal structure and morphology of Laves-phase-related bcc solid-solution alloys are reviewed.
Fundamentals of Slurry Design for CMP of Metal and Dielectric Materials
Authors: Singh Rajiv K. , Lee Seung-Mahn , Choi Kyu-Se , Bahar Basim G. , Choi Wonseop , Chen Zhan , Moudgil Brij M.
Published: February 2011

The formulation of slurries for chemical–mechanical planarization (CMP) is currently considered more of an art than a science, due to the lack of understanding of the wafer, slurry, and pad interactions involved. Several factors, including the large number of input variables for slurries and the synergistic interplay among input variables and output parameters, further complicate our ability to understand CMP phenomena. This article provides a fundamental basis for the choice of chemical additives and particles needed for present-day and next-generation slurry design. The effect of these components on nanoscale and microscale interaction phenomena is investigated. Methodologies are suggested for the development of next-generation slurries required to overcome CMP challenges related to defectivity and the surface topography of soft materials such as Low-κ dielectrics and copper.
Advances in Characterization of CMP Consumables
Authors: Moinpour Mansour , Tregub Alex , Oehler Andrea , Cadien Ken
Published: February 2011

Chemical–mechanical polishing, or planarization (CMP), has emerged as an increasingly important technology for integrated-circuit manufacturing. Consumables used during CMP interact in a complex manner with the polishing tool, the process conditions, and the wafer being polished. In this article, several advanced analytical methods are used to analyze the properties of slurries and pads under conditions similar to those found during CMP processing. Some of the key findings are that under these process conditions, pads can be stabilized with a heat treatment prior to installation on the polisher; pads absorb slurries at different rates, and slurries also react with the pads; and the mechanical properties of the pads are dependent on the orientation of the grooves on the pad. Dynamic rheometry was used to detect de-agglomeration in sheared slurries.
Development and Application of an Abrasive-Free Polishing Solution for Copper
Authors: Hanazono Masanobu , Amanokura Jin , Kamigata Yasuo
Published: February 2011

An abrasive-free polishing (AFP) solution for chemical–mechanical planarization (CMP) of copper films on semiconductor wafers has been developed to overcome such disadvantages of conventional CMP as dishing, erosion, Cu and oxide loss, and microscratching. Electrochemical methods are an effective way of understanding the role of each chemical component in the AFP solution in order to optimize its performance. Analysis of the reaction layer of Cu elucidates the reasons for the excellent results that have been obtained. By applying the AFP solution for Cu CMP in combination with a slurry for CMP of the metal barrier layer, seven-level multilayer Cu interconnections can be successfully fabricated.
Integration Challenges for CMP of Copper
Authors: Bajaj Rajeev , Zutshi Ajoy , Surana Rahul , Naik Mehul , Pan Tony
Published: February 2011

As the minimum feature size of microelectronic devices shrinks down to 130 nm, copper has been successfully adopted into logic applications.1–3 Copper requires damascene processing, which involves etching features into a dielectric substrate, filling the features with metal, and removing any excess metal. Therefore, chemical—mechanical planarization (CMP) is a key process in the final definition of the inlaid copper wires on a circuit. A second advance in the back-end processing of copper is the changing of the dielectric from SiO2 to a Low-κ material, which allows a thicker layer of dielectric to be used. Low-k dielectric films have much lower mechanical properties than SiO2; consequently, this poses new challenges in developing integration schemes.1,3–8
Elastic-Constant Behavior in Ti-Ni-Based Alloys
Authors: Otsuka Kazuhiro , Kakeshita Tomoyuki
Published: February 2011

The following is a Web Extra expanding upon the introductory article, “Science and Technology of Shape-Memory Alloys: New Developments,” by Kazuhiro Otsuka and Tomoyuki Kakeshita, Guest Editors, published in MRS Bulletin27 (2002) pp. 91–100.
Advanced Flat-Panel Displays and Materials
Authors: Kuo Yue , Suzuki Kouji
Published: February 2011

This introductory article reviews the topics covered in this issue of MRS Bulletin on advanced flat-panel displays and materials. The common requirements of flat-panel displays are compact dimensions, low power consumption, light weight, and high performance. Flat-panel displays are incorporated in many consumer products as well as in a large range of industrial, medical, military, transportation-related, and scientific instruments. In recent years, there have been dramatic improvements in flat-panel display technology due to an enhanced understanding of various new or existing materials as well as fabrication processes. “Flat-panel display” is a general term that includes many different types of technologies. It includes panels that are in mass production, such as passive or active addressed liquid-crystal displays or plasma displays, and those in the early production or development stages, such as organic light-emitting devices or electrophoretic displays. It also includes novel products that are based on the principle of flat-panel display technology, such as solid-state x-ray imagers. The articles in this issue cover a range of these topics.
Improving Color Tracking in In-Plane Switching Mode Liquid-Crystal Displays
Authors: Utsumi Yuka , Komura Shinichi , Hiyama Ikuo , Tsumura Makoto , Kondo Katsumi
Published: February 2011

Color tracking describes the ability of a display to faithfully reproduce the color quality of the source image. In liquid-crystal displays (LCDs), color tracking is dependent on brightness. In order to achieve high-performance color reproduction in LCDs, the accuracy of color tracking needs to be improved. By analyzing the characteristics of twisted-nematic (TN) and in-plane switching (IPS) modes of display, the cause of poor color tracking in each mode and the differences in their causes can be clarified. In TN mode displays, both chromaticity and brightness relate to the director configuration, that is, the directional alignment of the rod-like molecules of the liquid crystals, which varies with applied voltage. The ideal IPS LCD, by virtue of its operating principle, theoretically achieves perfect color tracking; however, in actual use, the color tracking is less than optimal due to twist deformation caused by the fixed directors on the alignment layer. Based on our analysis of these phenomena, we propose strategies for improving color tracking in IPS LCDs.
Low-Temperature Polycrystalline Silicon Thin-Film Transist or Technologies for System-on-Glass Displays
Authors: Uchikoga Shuichi
Published: February 2011

The elimination of conventional peripheral LSI (large-scale integration) drivers is considered essential to the development of future low-cost, energy-efficient, lightweight, and thin displays. System-on-glass (SOG) displays are a type of display with various functional circuits integrated on a glass substrate. Low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) make the integration of circuits possible because they can be assembled into complex, high-current driver circuits. Furthermore, LTPS TFTs are attracting attention for driving organic light-emitting devices (OLEDs). This article introduces present and future LTPS TFT technologies for SOG displays.
Solid-State X-Ray Imagers
Authors: Izumi Yoshihiro , Yamane Yasukuni
Published: February 2011

New solid-state x-ray imagers known as digital flat-panel x-ray detectors are about to be launched in the field of medical diagnostics. The combination of active-matrix technologies developed for active-matrix liquid-crystal displays and x-ray detection materials constitutes the basis of the detectors. Recently, two kinds of direct-conversion detectors have been developed in order to improve their performance. One is a detector using a thick x-ray photoconductor (∼1 mm) made of amorphous selenium, and the other is a novel hybrid panel detector using an x-ray photoconductor made of polycrystalline Cd(Zn)Te. As a result, excellent resolution and good linear sensitivity have been achieved. These detectors have great promise as next-generation digital imaging systems for fluoroscopy and radiography.
Paperlike Microencapsulated Electrophoretic Materials and Displays
Authors: Kazlas Peter T. , McCreary Michael D.
Published: February 2011

Microencapsulated electrophoretic (MEP) materials exhibit high optical reflectance and contrast, wide viewing angle, high resolution, and excellent image stability. MEP materials can be easily printed on large plastic sheets and laminated to a variety of electronic backplanes to construct displays. The combination of a MEP material with flexible transistor technologies enables displays that offer both the look and form of the printed page. This article reviews the basic architecture and properties of MEP materials and describes the integration of MEP materials with transistor backplanes to produce high-resolution, low-power, paperlike displays. Recent developments in ultrathin flexible displays are also reported.
Computer Simulations of the Martensitic Transformation
Authors: Jin Y. M. , Artemev A. , Khachaturyan A. G.
Published: February 2011

The following is a Web Extra expanding upon the introductory article, “Science and Technology of Shape-Memory Alloys: New Developments,” by Kazuhiro Otsuka and Tomoyuki Kakeshita, Guest Editors, published in MRS Bulletin27 (2002) pp. 91–100.
Plasma Display Materials
Authors: Nonomura Kinzo , Higashino Hidetaka , Murai Ryuichi
Published: February 2011

Recent trends in the development of plasma display panels (PDPs) are reviewed in this article with special emphasis on materials. New developments in the panel structure, discharge gases and phosphors used, and drive methods have improved many of the display characteristics over a wide range of operating conditions. As a result, much progress has been seen in large-scale panel development; for example, 50-in. and 61-in. PDPs have been commercialized. Improvements in phosphor longevity, discharge gas efficiency, and characteristics of the protective layers can be attributed in part to materials solutions. The longevity of the blue phosphor has been improved by the development of new materials and a greater understanding of the phosphor deterioration mechanism. The luminous efficiency has been greatly increased by the use of high-density Xe gas. The protective-layer characteristics have been improved as a result of advancements in processes, materials, and analytical methods.
Testing the Fundamental Theories of Surface Dynamics
Authors: Bartelt N. C.
Published: February 2011

The following article is based on the MRS Medal talk by Norm Bartelt (Sandia National Laboratories, California), presented at the 2001 Materials Research Society Fall Meeting on November 29 in Boston. Bartelt received the Medal for his “contributions to the statistical mechanics of materials surfaces.” A long-standing goal of materials science research has been to predict the long-term evolution of the microstructure of materials from a knowledge of atomic processes. This is usually extremely difficult to do in any detail because of the large number of atomic processes to consider, many of which are poorly understood. On solid surfaces, however, progress in the prediction of microstructural evolution can now be made because of advances in real-time microscopy that allow the characterization of the time evolution of microstructure in unprecedented detail. These observations directly reveal the complex relationships between collective thermal fluctuations on atomic scales and deterministic behavior on macroscopic scales. In this presentation, attempts to construct models of these observations are discussed.
The Use of Superelasticity in Modern Medicine
Authors: Duerig T. W.
Published: February 2011

The value of Nitinol (Ni-Ti) in the field of medicine has proven to be far greater than just as the simple “springy metal” it was once considered to be. In particular, its use in vascular implants highlights many valuable yet subtle behaviors, including a “biased stiffness,” enhanced fatigue resistance, low magnetic susceptibility, and good biocompatibility. Nitinol today is nearly as well known to medical-device designers and physicians as are stainless steel and titanium, and it is the enabling ingredient in a growing number of successful and profitable life-saving devices.
Understanding Precursor Phenomena for the R-Phase Transformation in Ti-Ni-Based Alloys
Authors: Shindo Daisuke , Murakami Yasukazu , Ohba Takuya
Published: February 2011

Precursor phenomena are critical issues for martensitic transformations. In this article, we show recent progress in understanding precursor phenomena to the R-phase transformation, which is important for both fundamentals and applications. Structural modulation in the parent phase was intensively studied by means of detailed analyses of the weak diffuse scattering of electrons with the aid of recently developed energy-filtered transmission electron microscopy coupled with x-ray diffraction. A peculiar domain-like structure, which originates from static transverse atomic displacements in the parent phase, was discovered by virtue of these advanced methods. The characteristics of this structure (e.g., size, shape, and temperature-dependence), as well as its role in the subsequent R-phase transformation, are discussed.
A Thermodynamic Approach to Selecting Alternative Gate Dielectrics
Authors: Schlom Darrell G. , Haeni Jeffrey H.
Published: February 2011

As a first step in the identification of suitable alternative gate dielectrics for metal oxide semiconductor field-effect transistors (MOSFETs), we have used tabulated thermodynamic data to comprehensively assess the thermodynamic stability of binary oxides and nitrides in contact with silicon at temperatures from 300 K to 1600 K. Sufficient data exist to conclude that the vast majority of binary oxides and nitrides are thermodynamically unstable in contact with silicon. The dielectrics that remain are candidate materials for alternative gate dielectrics. Of these remaining candidates, the oxides have a significantly higher dielectric constant (ĸ) than the nitrides. We then extend this thermodynamic approach to multicomponent oxides comprising the candidate binary oxides. The result is a relatively small number of silicon-compatible gate dielectric materials with ĸ values substantially greater than that of SiO2 and optical bandgaps ≥ eV.
Materials Characterization of Alternative Gate Dielectrics
Authors: Busch Brett W. , Pluchery Olivier , Chabal Yves J. , Muller David A. , Opila Robert L. , Raynien Kwo J. , Garfunkel Eric
Published: February 2011

Continued scaling of microelectronic devices is demanding that alternatives to SiO2 as the gate dielectric be developed soon. This in turn has placed enormous pressure on the abilities of physical characterization techniques to address critical issues such as film and interface structure and composition, transport properties, and thermal or chemical stability. This article summarizes the strengths and capabilities of four techniques used for the materials characterization of alternative gate dielectrics: scanning transmission electron microscopy (STEM) in conjunction with electron energy-loss spectroscopy (EELS), medium-energy ion scattering (MEIS), infrared-absorption spectroscopy (IRAS), and x-ray photoelectron spectroscopy (XPS). The complementary nature of these techniques has allowed for a detailed picture of the various properties of alternative gate dielectrics, and in particular of the dielectric/silicon interface. Critical issues and features of several important alternative gate dielectrics, ZrO2, AI2O3, Y2O3, and Gd2O3, are explored in light of the well-studied SiO2/Si system.
Issues in High-ĸ Gate Stack Interfaces
Authors: Misra Veena , Lucovsky Gerry , Parsons Gregory
Published: February 2011

We address current challenges in the fundamental understanding of physical and chemical processes that occur in the fabrication of the transistor gate stack structure. Critical areas include (1) the interface between bulk silicon and high-dielectric-constant (high-ĸ) insulators, (2) the interface between high-ĸ insulators and advanced gate electrodes, and (3) the internal interfaces that form within dielectric stacks with nonuniform material and structure compositions. We approach this topic from a fundamental understanding of bonding and electronic structure at the interfaces, and of film-growth kinetics in comparison with thermodynamics predictions. Implications for the dielectric/electrode interface with metallic gates and issues with integration will also be presented.
Electronic Structure and Band Offsets of High-Dielectric-Constant Gate Oxides
Authors: Robertson John
Published: February 2011

Identifying candidate materials to replace SiO2 as the gate dielectric for complementary metal oxide semiconductor (CMOS) applications is a difficult task. Proper assessment of the critical materials requirements is essential, and it is important to devise an approach to predict materials properties without having to make many unnecessary measurements on high-ĸ materials. Such an approach helps to eliminate unlikely candidates and focus on the most promising ones. Clearly, this type of modeling approach requires an understanding of several physical and chemical characteristics, including the bonding and electronic structure, band alignment with Si, and the nature of the dielectric constant and interface properties. We present a critical assessment of some existing methods and models of materials properties, as well as a comparison of the present modeling approach with some experimentally determined values.
The Opportunity and Threat of Disruptive Technologies
Authors: Christensen Clayton M.
Published: February 2011

I am honored to be with you today. I will give context for where the puzzles developed that have led to the research that I summarized in the book The Innovator's Dilemma. Companies that at one point were very successful and widely admired, fell from their leadership position within 5 to 10 years. This was very poignant for minicomputer companies, for example, which collapsed after their peak in the world economy during the 1970s and 1980s. While the companies were thriving, the business press attributed their successes to the abilities of their management teams. However, when these companies began to quickly unravel around 1988, the business press attributed their failures to the ineptitude of the very same management teams that had been in place during the years of success. I wondered how good managers could get that bad that fast.
Combinatorial Synthesis and Evaluation of Functional Inorganic Materials Using Thin-Film Techniques
Authors: Takeuchi Ichiro , Dover Robert Bruce van , Koinuma Hideomi
Published: February 2011

Novel phases of functional inorganic chemical systems can be efficiently explored using high-throughput thin-film fabrication techniques coupled with rapid characterization schemes. High-throughput investigation of thin-film materials has already led to the discovery of new dielectric and magnetic materials. In this article, we review various high-throughput thin-film synthesis/evaluation techniques and discuss examples of exciting discoveries and new applications of combinatorial techniques.
Silica-Based Planar Lightwave Circuits and Their Applications
Authors: Hibino Yoshinori
Published: February 2011

This article reviews the fabrication technologies and optical characteristics of silica-based planar lightwave circuits (PLCs) on Si developed for photonic networks based on wavelength-division multiplexing (WDM). While there have been various planar optical waveguides made with different materials, silica-based PLCs are the most suitable for constructing practical devices because of their excellent design flexibility, stability, and reproducibility. These advantages mainly result from their material characteristics, that is, silica glass is chemically and physically stable. The article also describes the basic characteristics and recent development of arrayed waveguide grating (AWG) multiplexers/demultiplexers as a device application. Since AWGs offer the advantages of low-loss, high-output port counts and mass producibility, they have played a pivotal role in the construction of flexible, large-capacity WDM networks.
Dielectric Materials for Thin-Film-Based Optical Communications Filters
Authors: Sargent Robert B. , O'Brien Nada A.
Published: February 2011

Explosive growth in the fiber-optic telecommunications infrastructure during the past decade has driven noteworthy advances in thin-film-based optical interference filter technology. In particular, the widespread deployment of wavelength-division multiplexing (WDM), a means of increasing the communication capacity of an optical fiber by utilizing more than one wavelength of light, has motivated significant improvements in bandpass filter performance. A common requirement is for filters that combine or separate wavelengths spaced 100 GHz (0.8 nm) apart. The foundation for these recent breakthroughs has been laid by the development of optical coating technology over the past century. This article reviews the materials and processes used in the production of thin-film-based optical communications filters.
Adhesives for Elevated-Temperature Applications
Authors: Millington S. , Shaw S. J.
Published: February 2011

Although adhesives, particularly those based on epoxy resins, are finding increasing use in structural applications, their utilization at elevated temperature (>150°C) has been limited by their relatively poor thermal and thermo-oxidative stability. As a result, significant effort has been directed in recent years toward the development of polymers exhibiting increased thermal resistance. Although a wealth of research conducted over several decades has resulted in a myriad of polymer types exhibiting, in some cases, impressive high-temperature performance, many systems have demonstrated poor processability Thus, much emphasis has been placed on developing high-temperature performance while providing processability characteristics that are similar, if not identical, to epoxies. This article considers the various approaches that have been shown to offer such dual capabilities. In addition, the results of various studies undertaken to investigate the effects of elevated temperature on the strength and fatigue resistance of bonded joints are reported.
Toughening Epoxy Adhesives to Meet Today's Challenges
Authors: Kinloch A. J.
Published: February 2011

There are many advantages that polymeric adhesives can offer compared with the more traditional methods of structural joining such as bolting, brazing, welding, and mechanical fastening, and epoxy adhesives represent the most common type of structural adhesive. When polymerized, epoxy adhesives are amorphous and highly cross-linked materials, and this microstructure results in many useful properties for structural engineering applications, such as a high modulus and failure strength, low creep, and, by careful formulation, good performance at elevated temperatures. However, the structure of such thermosetting adhesives also generally leads to one highly undesirable property: they are relatively brittle materials, with poor resistance to crack initiation and growth. Nevertheless, the incorporation of a second phase of dispersed rubbery particles into the epoxy polymer can greatly increase their toughness without significantly impairing their other desirable engineering properties. Thus, rubber-toughened epoxy adhesives can be used, for example, in applications where very high impact resistance is required for the bonded joint.
Microelectronics Packaging and Integration
Authors: Reuss Robert H. , Chalamala Babu R.
Published: February 2011

The focus of this issue of MRS Bulletin is to explore the impact of materials science and technology on microelectronics packaging and integration. Progress in microelectronics packaging has been intimately tied to the continuous advances made in the associated materials, process technologies, and design tools. This is especially true now, as packaging moves into an era driven by the need for complex system-level solutions. This issue is our attempt to present the current status of microelectronics packaging technology and integration and to highlight various perspectives on the future evolution of the field.
Hydrogen Effects on Deformation and Fracture: Science and Sociology
Authors: Birnbaum H.K.
Published: February 2011

The following article is an edited transcript based on the Von Hippel Award presentation given by Howard K. Birnbaum of the University of Illinois at Urbana-Champaign on December 4, 2002, at the Materials Research Society Fall Meeting in Boston. The award citation states, “Through innovative use of a wide range of novel experimental tools, Howard K. Birnbaum has made seminal contributions to our understanding of intrinsic point defects, hydrogen in metals, and grain-boundary segregation, especially as these effects relate to mechanical properties. He has also stimulated, directed, and influenced interdisciplinary research throughout the materials community.” This presentation summarizes the major phenomenological observations associated with hydrogen effects on fracture and the viable mechanisms that can account for these observations. It is shown that there are three fracture mechanisms that are consistent with the experimental observations and that the operative fracture mechanism depends on the type of system and the conditions under which it is exposed to hydrogen in aggressive environments.
Organic-Based Magnets: Opportunities in Photoinduced Magnetism, Spintronics, Fractal Magnetism, and Beyond
Authors: Epstein Arthur J.
Published: February 2011

This article is based on a presentation on organic-based magnets given as part of Symposium X—Frontiers of Materials Research on December 4, 2002, at the 2002 Materials Research Society Fall Meeting in Boston. The advent of organic-based magnets opened the opportunity for tuning magnetic properties by molecular design and the discovery of new phenomena that rely on the internal structure of the molecules that make up these magnets. In the past 18 years, numerous classes of organic-based ferromagnets, ferrimagnets, and spin glasses (spins essentially frozen in place without long-range order) have been reported. These materials have magnetic ordering temperatures ranging from <1 K to above room temperature and demonstrate many of the magnetic properties associated with conventional magnets. This article concentrates on new phenomena that are unique to organic-based magnets. Three of these effects—“high-temperature” light-induced magnetism, spin-polarized magnetic organic semiconductors with the potential for spintronics, and the development of fractal magnetic order—are discussed to illustrate the richness of opportunity in organic-based magnets.
Studies of Ancient Glass and Their Application to Nuclear-Waste Management
Authors: Römich Hannelore
Published: February 2011

During several hundred years of burial in the soil, glass objects, especially those with the high potassium content of medieval compositions, develop heavily corroded surfaces, showing phenomena such as local pitting, laminated layers, and browning effects. The long-term behavior of glass in the soil or in contact with groundwater is not only of interest to glass scientists with a background in archaeology, but also for those with a special interest in nuclear-waste management. Several attempts have been made to propose the decomposition of ancient glasses as an indicator for the performance of buried nuclear-waste glasses. In spite of differences in glass composition and exposure conditions, the development of alteration or corrosion layers with time is a common concern, as shown in this article. Laboratory experiments, representing a simplified model for real conditions, offer the possibility for systematic investigations.