bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assembled Semiconductor Nanowire Thin Films for High-Performance Flexible Macroelectronics
Authors: Duan Xiangfeng 
Published: February 2011

AbstractA new concept of macroelectronics using assembled semiconductor nanowire thin films holds the promise of significant performance improvement. In this new concept, a thin film of oriented semiconductor nanowires is used to produce thin-film transistors (TFTs) with conducting channels formed by multiple parallel single-crystal nanowire paths. There fore, charges travel from source to drain within single crystals, ensuring high carrier mobility. Recent studies have shown that high-performance silicon nanowire TFTs and high-frequency circuits can be readily produced on a variety of substrates including glass and plastics using a solution assembly process. The device performance of these nanowire TFTs not only greatly surpasses that of solution-processed organic TFTs, but is also significantly better than that of conventional amorphous or polycrystalline silicon TFTs, approaching single-crystal silicon-based devices. Furthermore, with a similar frame-work, Group III-V or II-VI nanowire or nanoribbon materials of high intrinsic carrier mobility or optical functionality can be assembled into thin films on flexible substrates to enable new multifunctional electronics/optoelectronics that are not possible with traditional macroelectronics. This can have an impact on a broad range of existing applications, from flat-panel displays to image sensor arrays, and enable a new generation of flexible, wearable, or disposable electronics for computing, storage, and wireless communication.
Nanowire-Based Nanoelectronic Devices in the Life Sciences
Authors: Patolsky Fernando , Timko Brian P. , Zheng Gengfeng , Lieber Charles M. 
Published: February 2011

AbstractThe interface between nanosystems and biosystems is emerging as one of the broadest and most dynamic areas of science and technology, bringing together biology, chemistry, physics, biotechnology, medicine, and many areas of engineering. The combination of these diverse areas of research promises to yield revolutionary advances in healthcare, medicine, and the life sciences through the creation of new and powerful tools that enable direct, sensitive, and rapid analysis of biological and chemical species. Devices based on nanowires have emerged as one of the most powerful and general platforms for ultrasensitive, direct electrical detection of biological and chemical species and for building functional interfaces to biological systems, including neurons. Here, we discuss representative ex amples of nanowire nanosensors for ultrasensitive detection of proteins and individual virus particles as well as recording, stimulation, and inhibition of neuronal signals in nanowire-neuron hybrid structures.
The Mechanics and Physics of Defect Nucleation
Authors: Li Ju 
Published: February 2011

AbstractThe following article is based on the Outstanding Young Investigator Award presentation given by Ju Li on April 19, 2006, at the Materials Research Society Spring Meeting in San Francisco. Li received the award “for his innovative work on the atomistic and first-principles modeling of nanoindentation and ideal strength in revealing the genesis of materials deformation and fracture.”Defect nucleation plays a critical role in the mechanical behavior of materials, especially if the system size is reduced to the submicron scale. At the most fundamental level, defect nucleation is controlled by bond breaking and reformation events, driven typically by mechanical strain and electronegativity differences. For these processes, atomistic and first-principles calculations are uniquely suited to provide an unprecedented level of mechanistic detail. Several connecting threads incorporating notions in continuum mechanics and explicit knowledge of the interatomic energy landscape can be identified, such as homogeneous versus heterogeneous nucleation, cleavage versus shear-faulting tendencies, chemomechanical coupling, and the fact that defects are singularities at the continuum level but regularized at the atomic scale. Examples are chosen from nano-indentation, crack-tip processes, and grain-boundary processes. In addition to the capacity of simulations to identify candidate mechanisms, the computed athermal strength, activation energy, and activation volume can be compared quantitatively with experiments to define the fundamental properties of defects in solids.
TEM Sample Preparation and FIB-Induced Damage
Authors: Mayer Joachim , Giannuzzi Lucille A. , Kamino Takeo , Michael Joseph 
Published: February 2011

AbstractOne of the most important applications of a focused ion beam (FIB) workstation is preparing samples for transmission electron microscope (TEM) investigation. Samples must be uniformly thin to enable the analyzing beam of electrons to penetrate. The FIB enables not only the preparation of large, uniformly thick, sitespecific samples, but also the fabrication of lamellae used for TEM samples from composite samples consisting of inorganic and organic materials with very different properties. This article gives an overview of the variety of techniques that have been developed to prepare the final TEM specimen. The strengths of these methods as well as the problems, such as FIB-induced damage and Ga contamination, are illustrated with examples. Most recently, FIB-thinned lamellae were used to improve the spatial resolution of electron backscatter diffraction and energy-dispersive x-ray mapping. Examples are presented to illustrate the capabilities, difficulties, and future potential of FIB.
Focused Ion Beam Micro- and Nanoengineering
Authors: Langford Richard M. , Nellen Philipp M. , Gierak Jacques , Fu Yongqi 
Published: February 2011

AbstractThis article discusses applications of focused ion beam micro- and nanofabrication. Emphasis is placed on illustrating the versatility of focused ion beam and dual-platform systems and how they complement conventional processing techniques. The article is divided into four parts: maskless milling, ion beam lithography, ion implantation, and techniques such as in situ micromanipulation.
Sticky Feet: From Animals to Materials
Authors: Creton Costantino , Gorb Stanislav 
Published: February 2011

AbstractMany insects and some larger animals, such as geckos, skinks, and tree frogs, can easily climb vertical walls and even walk on the ceiling. These abilities require a method to attach the feet strongly but reversibly to a variety of surfaces—smooth or rough, hydrophilic or hydrophobic, clean or containing contaminants. This issue ofMRS Bulletinexamines how fibrils, absorbed water layers, geometry, and other factors make reversible adhesion possible, and how this understanding might be applied to robots and other artificially created structures that can climb walls, walk on ceilings, and get to other hard-to-reach places.
Mechanics of Bioinspired and Biomimetic Fibrillar Interfaces
Authors: Jagota A. , Hui C.-Y. , Glassmaker N. J. , Tang T. 
Published: February 2011

AbstractMaterials that are inspired by or are mimics of natural fibrillar surfaces in lizards and insects aim to achieve enhanced interfacial adhesion and contact properties by means of a fibrillar architecture. Studies of the mechanics of deformation and adhesion of such materials help to explain how they work and are aiding the design of their architecture. This article discusses some of the issues addressed by these studies, such as how can a fibrillar interface be made stronger and tougher than a flat control, and how does one enhance its ability to make contact to a variety of substrates?
Molecular Design of Inorganic-Binding Polypeptides
Authors: Evans John Spencer , Samudrala Ram , Walsh Tiffany R. , Oren Ersin Emre , Tamerler Candan 
Published: February 2011

AbstractControlled binding and assembly of peptides onto inorganic substrates is at the core of bionanotechnology and biological-materials engineering. Peptides offer several unique advantages for developing future inorganic materials and systems. First, engineered polypeptides can molecularly recognize inorganic surfaces that are distinguishable by shape, crystallography, mineralogy, and chemistry. Second, polypeptides are capable of self-assembly on specific material surfaces leading to addressable molecular architectures. Finally, genetically engineered peptides offer multiple strategies for their functional modification. In this article, we summarize the details and mechanisms involved in combinatorial-polypeptide sequence selection and inorganic-material recognition and affinity, and outline experimental and theoretical approaches and concepts that will help advance this emerging field.
Molecular Design of β-Hairpin Peptides for Material Construction
Authors: Rughani Ronak V. , Schneider Joel P. 
Published: February 2011

AbstractSelf-assembled materials composed of β-sheet forming peptides hold promise as therapeutics and novel biomaterials. This article focuses on the design and engineering of amphiphilic peptide sequences, especially β-hairpins. Peptides can be designed to intramolecularly fold and then self-assemble on cue, affording hydrogels rich in β-sheet structure. Hydrogels having distinct material properties can be designed at the molecular level by modulating either the peptide's sequence or the environmental stimulus used to trigger folding and assembly, leading to gelation.
Glass-Formers and Viscous Liquid Slowdown since David Turnbull: Enduring Puzzles and New Twists
Authors: Angell C.A. 
Published: February 2011

AbstractTo Turnbull's study of the kinetic problem of nucleation and growth of crystals, we add the further enquiry into what lies behind the slow nucleation kinetics of glass-formers. Our answer to this question leads to the proposal of conditions in which a pure liquid metal, monatomic and elemental, can be vitrified. Using the case of high-pressure liquid germanium, we give electron microscope evidence for the validity of our thinking.On the question of how liquids behave when crystals do not form, Turnbull pioneered the study of glass transitions in metallic alloys, measuring the heat capacity change at the glass transition Tg for the first time, and developing with Cohen the free volume model for the temperature dependence of liquid transport properties approaching Tg. We extend the phenomenological picture to include networks where free volume does not play a role and reveal a pattern of behavior that provides for a classification of glass-formers (from “strong” to “fragile”). Where Turnbull studied supercooled liquid metals and P4 to the homogeneous nucleation limit using small droplets, we studied supercooled water in capillaries and emulsions to the homogeneous nucleation limit near −40°C. We discuss the puzzling divergences observed that are now seen as part of a cooperative transition that leads to very untypical glass-transition behavior at lower temperatures (when crystallization is bypassed by hyperquenching). Finally, we show how our interpretation of water behavior can be seen as a bridge between the behavior of the “strong” (network) liquids of classical glass science (e.g., SiO2) and the “fragile” behavior of typical molecular glass-formers. The link is made using a “Gaussian excitations” model by Matyushov and the author in which the spike in heat capacity for water is pushed by cooperativity (disorder stabilization of excitations) into a first-order transition to the ground state, at a temperature typically below Tg. In exceptional cases like triphenyl phosphite, this liquid-to-glass first-order transition lies above Tg and can be studied in detail.
Combining Serial Sectioning, EBSD Analysis, and Image-Based Finite Element Modeling
Authors: Spanos G. , Rowenhorst D.J. , Lewis A.C. , Geltmacher A.B. 
Published: February 2011

AbstractThis article first provides a brief review of the status of the subfield of three-dimensional (3D) materials analyses that combine serial sectioning, electron backscatter diffraction (EBSD), and finite element modeling (FEM) of materials microstructures, with emphasis on initial investigations and how they led to the current state of this research area. The discussions focus on studies of the mechanical properties of polycrystalline materials where 3D reconstructions of the microstructure—including crystallographic orientation information—are used as input into image-based 3D FEM simulations. The authors' recent work on a β-stabilized Ti alloy is utilized for specific examples to illustrate the capabilities of these experimental and modeling techniques, the challenges and the solutions associated with these methods, and the types of results and analyses that can be obtained by the close integration of experiments and simulations.
Solution-Processed Organic Solar Cells
Authors: Brabec Christoph J. , Durrant James R. 
Published: February 2011

AbstractOrganic solar cells, based on polymer/fullerene-blend films, are advancing rapidly toward commercial viability. In this article, we review recent progress on two issues critical for technological applications: device photovoltaic efficiencies and processing technologies for high-throughput production. In terms of device efficiencies, we consider advances in low-bandgap polymers, film morphology, and device structure aimed at increasing efficiencies beyond 5%. We then review recent progress in developing high-throughput, solution-printing-based processes for low-cost device fabrication.
Synthetic Aspects of Organic Semiconductors
Authors: Anthony John E. , Heeney Martin , Ong Beng S. 
Published: February 2011

AbstractThis article discusses the importance of the choice of synthetic methodology in the purity, and therefore performance, of both small-molecule and polymeric organic semiconductors. We discuss common methodologies used in the preparation of organic semiconductors, paying particular attention to the impurities and by-products that can arise during these synthetic approaches and how they can have an impact on semiconductor performance.
Progress and Challenges in Commercialization of Organic Electronics
Authors: Loo Yueh-Lin , McCulloch Iain 
Published: February 2011

AbstractThe field of organic electronics is entering its commercial phase. The recent market introduction of the first prototypes based on organic transistors fabricated from solution is set to augment the existing market presence of organic light-emitting diode applications. Organic photovoltaic products are not far behind. In this article, we provide a brief overview of these devices, with our main focus being organic transistor applications. In particular, we examine some of the key performance requirements for working devices. We also review some of the important advances in semiconductor design and device fabrication techniques and discuss some of the technical challenges that remain in the optimization of next-generation products.
Self-Healing Fiber-Reinforced Polymer Composites
Authors: Bond Ian P. , Trask Richard S. , Williams Hugo R. 
Published: February 2011

AbstractSelf-healing is receiving an increasing amount of interest worldwide as a method to address damage in materials. In particular, for advanced high-performance fiber-reinforced polymer (FRP) composite materials, self-healing offers an alternative to employing conservative damage-tolerant designs and a mechanism for ameliorating inaccessible and invidious internal damage within a structure. This article considers in some detail the various self-healing technologies currently being developed for FRP composite materials. Key constraints for incorporating such a function in FRPs are that it not be detrimental to inherent mechanical properties and that it not impose a severe weight penalty.
Electron-Beam Lithographic Studies of the Scaling of Phase-Change Memory
Authors: Raoux Simone , Rettner Charles T. , Chen Yi-Chou , Burr Geoffrey W. 
Published: February 2011

AbstractPhase-change random-access memory (PCRAM) is a promising technology for future nonvolatile storage with the added potential for possible impact on dynamic random-access memory technologies. To be successful, however, PCRAM must be able to scale to dimensions on the order of a few tens of nanometers, considering the increasingly tiny memory cells that are projected for future technology nodes. The experiments discussed in this article directly address these scaling properties, examining both the materials themselves and the operation of nanoscale devices. One series of experiments is time-resolved x-ray diffraction studies of ultrathin films and nanostructures. Electron-beam lithography was applied to pattern thin films into nanostructures with dimensions down to 20 nm. The article also includes descriptions of prototype PCRAM devices, successfully fabricated and tested down to phase-change material cross sections of 3 nm × 20 nm. The measurements provide a clear demonstration of the excellent scaling potential offered by this technology.
Negative-Index Materials: Optics by Design
Authors: Park Wounjhang , Kim Jinsang 
Published: February 2011

AbstractIndex of refraction, a fundamental optical constant that enters in the descriptions of almost all optical phenomena, has long been considered an intrinsic property of a material. However, the recent progress in negative-index material (NIM) research has shown that the utilization of deep-subwavelength-scale features can provide a means to engineer fundamental optical constants such as permittivity, permeability, impedance, and index of refraction. Armed with new nanofabrication techniques, researchers worldwide have developed and demonstrated a variety of NIMs. One implementation uses a combination of electric and magnetic resonators that simultaneously produce negative permittivity and permeability, and consequently negative refractive index. Others involve chirality, anisotropy, or Bragg resonance in periodic structures. NIM research is the beginning of new optical materials research in which the desired optical properties and functionalities are artificially generated. Clearly, creating negative index materials is not the only possibility, and the most recent developments explore new realms of materials with near-zero indexes and inhomogeneous index profiles that can produce novel phenomena such as invisibility. Furthermore, the concept of controlling macroscopic material properties with a composite structure containing subwavelength-scale features extends to the development of acoustic metamaterials. By providing a review of recent progress in NIM research, we hope to share the excitement of the field with the broader materials research community and also to spur new ideas and research directions.
New Frontiers of Metamaterials: Design and Fabrication
Authors: Chaturvedi Pratik , Hsu Keng , Zhang Shu , Fang Nicholas 
Published: February 2011

AbstractArtificially engineered metamaterials have emerged with properties and functionalities previously unattainable in natural materials. The scientific breakthroughs made in this new class of electromagnetic materials are closely linked with progress in developing physics-driven design and novel parallel fabrication methods. For example, a smooth superlens has been demonstrated with 30-nm imaging resolution, or 1/12 of the corresponding wavelength, far below the diffraction limit. Similarly, a photoswitchable optical negative-index material has been printed, showing a remarkable tuning range of refractive index in the communication wavelength. New frontiers are being explored as intrinsic limitations challenge the scaling of microwave metamaterial designs to optical frequencies. These novel metamaterials promise an entire new generation of passive and active optical elements, such as paper-thin superlenses and modulators.
In Situ Transmission Electron Microscopy
Authors: Ferreira P.J. , Mitsuishi K. , Stach E.A. 
Published: February 2011

AbstractThe articles in this issue of MRS Bulletin provide a sample of what is novel and unique in the field of in situ transmission electron microscopy (TEM). The advent of improved cameras and continued developments in electron optics and stage designs have enabled scientists and engineers to enhance the capabilities of previous TEM analyses. Currently, novel in situ experiments observe and record the behavior of materials in various heating, cooling, straining, or growth environments. In situ TEM techniques are invaluable for understanding and characterizing dynamic microstructural changes. They can validate static TEM experiments and inspire new experimental approaches and new theories.
Optical Metamagnetism and Negative-Index Metamaterials
Authors: Chettiar Uday K. , Xiao Shumin , Kildishev Alexander V. , Cai Wenshan , Yuan Hsiao-Kuan , Drachev Vladimir P. , Shalaev Vladimir M. 
Published: February 2011

AbstractA new class of artificially structured materials called metamaterials makes it possible to achieve electromagnetic properties that do not exist in nature. In this article, we review the recent progress made in the area of optical metamaterials, specifically artificial magnetism and negative-index metamaterials. It was predicted that nanostructured metamaterials could provide magnetic responses and negative refractive indexes at optical frequencies. To date, optical metamagnetics have been fabricated to demonstrate magnetic responses in the infrared range and across the entire visible spectrum. Metamaterials showing negative refractive indexes, also called negative-index materials (NIMs), have also been demonstrated in the infrared range and at the border with the visible spectral range. Additionally, we report the results of a sample that displays NIM behavior for red light at a wavelength of 710 nm and another sample that displays double-negative NIM behavior at 725 nm. Both observations represent the shortest wavelengths so far at which NIM behavior has been observed for light. We also discuss the fabrication challenges and the impact of fabrication limitations, specifically the effect of surface roughness of the fabricated structures, on the optical properties of the metamaterials.
Acoustic Metamaterials
Authors: Fok Lee , Ambati Muralidhar , Zhang Xiang 
Published: February 2011

AbstractThe field of engineered materials with designed properties is expected to continue to grow in the future, and metamaterials are instrumental in allowing this freedom of design. Metamaterials, particularly acoustic, are still in the stage of infancy. Acoustic metamaterials are being explored theoretically, but there has been little headway on the experimental front. The design, development, and characterization of acoustic metamaterials will offer many opportunities in materials science. In this article, we review the basic physics of different kinds of acoustic periodic structures with special emphasis on locally resonant acoustic metamaterials. We first survey phononic crystals and then discuss localized resonances in intrinsic and inertial resonating structures of acoustic metamaterials. Finally, we present the ongoing efforts in realizing acoustic metamaterials with negative materials properties and discuss the implications of acoustic metamaterials.
Strongly Correlated Electronic Materials: Present and Future
Authors: Dagotto E. , Tokura Y. 
Published: February 2011

AbstractIn complex transition-metal oxides, the interactions between the electronic spins, charges, and orbitals produce a rich variety of electronic phases. The competition and/or cooperation among these correlated-electron phases can lead to the emergence of surprising electronic phenomena and functionalities and form the basis for a new type of electronics.