bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethics of Nanotechnology State of the Art and Challenges Ahead
Authors: Grunwald Armin
Published: June 2010

Parallel to the public discussion on the benefits and risks of nanotechnology, a debate on the ethics of nanotechnology has begun. In this contribution, an attempt is made to establish a “map” of the relevant ethical aspects of nanotechnology in a systematic manner. It turns out that there are hardly any completely new ethical aspects raised by nanotechnology. It is much rather primarily a case of gradual shifts of emphasis and of relevance in questions which, in principle, are already known and which give reason for ethical discussions on nanotechnology. In a certain manner, structurally novel ethical aspects arise through the important role played by visions in the public discourse. New questions are also posed by the fact that previously separate lines of ethical reflection converge in the field of nanotechnology.
Outlook and Consequences
Authors: Schmid Günter
Published: June 2010

In his personal outlook, the author cautions against unscientific and biased views when assessing the future progress of nanoscience and nanotechnology. Several examples of nanotechnological innovations are cited that demonstrate the power and potential of this technology. The author concludes with an appeal to better educate the public about the potential benefits and dangers of nanotechnology.
Pollution Prevention and Treatment Using Nanotechnology
Authors: Bernd Nowack
Published: June 2010

The sections in this article are

Introduction

More Efficient Resource and Energy Consumption

Pollution Detection and Sensing

Water Treatment

Adsorption of Pollutants

Magnetic Nanoparticles

Nanofiltration

Degradation of Pollutants

Zerovalent Iron

Soil and Groundwater Remediation

Environmental Risks

Behavior in the Environment

Ecotoxicology

Conclusions
Photocatalytic Surfaces: Antipollution and Antimicrobial Effects
Authors: Allen Norman S. , Edge Michele , Verran Joanne , Stratton John , Maltby Julie , Bygott Claire
Published: June 2010

A series of nano and micron particle grade anatase and rutile titanium dioxide pigments have been prepared with various densities of surface treatments, particle size and surface area. Their photocatalytic activities have been determined in a series of paint films and cementitious materials for self‐cleaning, depollution and antimicrobial/‐bacterial activity. The photocatalytic activities have also been examined by rapid assessment methodologies using 2‐propanol oxidation and hydroxyl group analysis. Photo‐oxidation studies on several types of paint films show a clear demarcation between nanoparticle and pigmentary grade titanium dioxide, with the former being more active due to its greater degree of catalytic surface activity. The photosensitivity of titanium dioxide is considered to arise from localized sites on the crystal surface (i.e. acidic OH) and occupation of these sites by surface treatments inhibits photo‐reduction of the pigment by UV radiation and hence the destructive oxidation of the binder is inhibited. The use of photocatalytic titania nanoparticles in the development of self‐cleaning paints and microbiological surfaces is demonstrated. In the former case surface erosion is shown to be controlled by varying the ratio of admixture of durable pigmentary grade rutile (heavily coated) and a catalytic grade anatase nanoparticle. For environmental applications in the development of coatings and cementitious materials for destroying atmospheric pollutants such as nitrogen oxides (NO

x

), stable substrates are illustrated with photocatalytic nanoparticle grade anatase. Here porosity of the coatings through calcium carbonate doping is shown to be crucial in the control of the effective destruction of atmospheric NO

x

gases. Good environmental stability of the coatings is also crucial for long‐term durability and this aspect is examined for a variety of material substrates. For the development of microbiological substrates for the destruction of harmful bacteria/fungi, effective nanoparticle anatase titania is shown to be important, with hydrated high surface area particles giving the greatest activity.
Pollution Treatment, Remediation and Sensing
Authors: Sugunan Abhilash , Dutta Joydeep
Published: June 2010

Environmental pollution has become a matter of grave concern and it is clear that the issue must be dealt with early in the 21st century, before it is too late. Nanotechnology is a promising discipline that shows promise of impacting diverse fields, including environmental pollution. In this chapter, various types of environmental pollution and the scope of nanotechnology in addressing these problems are discussed. The literature on the treatment, remediation and detection (sensors) of various environmental pollutants is surveyed, with focus on the timely detection of the pollutants. Cost‐effective strategies and niche approaches that offer good potential for application not only in real‐time pollution detection, but also in pollution treatment and remediation, are discussed.
Benefits in Energy Budget
Authors: Suni Ian Ivar
Published: June 2010

Nanomaterials in the 1–100 nm size range have extraordinary potential for applications within a wide variety of existing and emerging technologies. Such applications depend primarily on the existence of quantum confinement effects, which allow the optical and electronic properties of a material to be tuned with size, on the unusually high chemical reactivity of nanomaterials, and on their high ratio of surface area to volume. Among the applications of nanomaterials are the development of sustainable energy sources and their potential impact on the global energy budget. Applications of nanomaterials in the field of energy are discussed, including fuel cell catalyst supports, where carbon nanotubes show tremendous promise; hydrogen storage, where carbon nanotubes and other nanomaterials may be useful; photovoltaic solar cells, where quantum confinement can be employed to tune the absorption wavelength of nanomaterials and nanostructured titania solar cells have been demonstrated with high efficiency; and lithium ion battery anodes, where several nanomaterials, including metal and Si nanoparticles and carbon nanotubes, have been demonstrated to have extraordinarily high Li storage capacity.
An Industrial Ecology Perspective
Authors: Lloyd Shannon M. , Lekas Deanna N. , Schmitt Ketra A.
Published: June 2010

The sections in this article are

Introduction

Industrial Ecology

Applying Industrial Ecology to Nanotechnology

Life Cycle Assessment

Background on Life Cycle Assessment

Life Cycle Implications for Nanotechnology

Life Cycle Studies Conducted to Date

Substance Flow Analysis

Background on Substance Flow Analysis

Substance Flow Analysis Implications for Nanotechnology

Summary of Substance Flow Analysis Work Conducted to Date

Corporate Social Responsibility

Background on Corporate Social Responsibility

Corporate Social Responsibility Implications for Nanotechnology

Summary of Work Conducted to Understand NanofirmEHSConcerns and Actions

Conclusions
Composition, Transformation and Effects of Nanoparticles in the Atmosphere
Authors: Pöschl Ulrich
Published: June 2010

Airborne nano‐ and microparticles (aerosols) are of central importance for atmospheric chemistry and physics, the biosphere, climate and public health. They influence the Earth's energy balance, the hydrological cycle and atmospheric circulation and the abundance of greenhouse and reactive trace gases. Moreover, they play important roles in the reproduction of biological organisms and can cause or enhance diseases. The primary parameters that determine the environmental and health effects of aerosol particles are their size, composition and concentration. These parameters, however, are spatially and temporally highly variable. This chapter outlines the current state of knowledge, major open questions and research perspectives concerning the composition, transformation and effects of particles in the atmosphere.
Measurement and Detection of Nanoparticles Within the Environment
Authors: Kuhlbusch Thomas A.J. , Fissan Heinz , Asbach Christof
Published: June 2010

In order to assess possible environmental implications of nanoparticles, it is necessary to be able to detect and quantify nanoparticles in the corresponding matrix. Nanoparticles may be present in soil, water and air in the ambient and/or especially workplace environments where product nanoparticles are handled. Hence different measurement and sampling techniques are necessary in addition to task‐specific strategies. This chapter discusses the above issues and explains the basic principles of the measurement techniques with a view to linking this information to environmental exposure of ecosystems, plants, animals and humans. A possible risk from nanoparticles may only occur and can only be assessed if the concentrations and characteristics of nanoparticles can be determined and quantified.
Epidemiological Studies on Particulate Air Pollution
Authors: Brüske‐Hohlfeld Irene , Peters Annette
Published: June 2010

There is a linear relationship between PM10and PM2.5and various health indicators and no threshold in particle concentrations below which health would not be jeopardized. The size of the effects is often larger for ultrafine than for fine particles on a per mass basis. Lung diseases attributed to environmental air pollution are deterioration of lung function and respiratory symptoms, exacerbations of chronic obstructive lung disease, asthma and allergies and lung cancer. Several mechanisms have been hypothesized to contribute to deaths from cardiovascular diseases. The inhalation of particles provokes oxidative stress and triggers systemic inflammation, leading to altered blood rheology favoring coagulation, vascular dysfunction and enhanced atherosclerosis – all increasing the risk of a subsequent myocardial infarction. The alteration of the autonomic nervous control of the heart increases the likelihood of ischemic events and cardiac arrhythmias. Dust at the workplace is responsible for serious and disabling diseases such as pneumoconiosis, interstitial lung disease and fibrosis, lung cancer and asthma. The potential hazard of different nanomaterials is not predictable by the bulk physicochemical properties and data on exposure assessment are still lacking.
Impact of Nanotechnological Developments on the Environment
Authors: Krug Harald F. , Klug Petra
Published: June 2010

Nanotechnology is about discovering, developing and using materials consisting in their primary stage at a size within the low nanometer range. These ultrafine particles offer new properties and opportunities. Although the synthesis of nanoparticles has been discovered during the last decades, exposure of humans to ultrafine particles occurred long before, as ultrafine particles in ambient air are generated during combustion processes. Within this chapter only engineered nanoparticles are considered, because much potential and hopes are associated with these new materials but much nescience is existing about their possible adverse effects to life or environment. At workplaces, during manufacturing, in technical applications or in drugs, nanoparticles will frequently have biological side effects which have to be well balanced against their advantages, before they can be used without concern. Therefore, information about safety and potential hazards is urgently needed. Along with the technical development of nanoparticles a public discussion has started, leading to extensive investigations on possible negative side effects on human health. Research activities have been strengthened in departments for environmental toxicology, hygiene institutes and other academic facilities to identify hazard and risks during handling and use of these new materials. On the other hand, as described within the other chapters, nanotechnology offers the promise of improved characterisation of environmental problems through improved detection and monitoring capabilities, significantly reduced environmental effects from cleaner manufacturing and synthesis approaches that result in a reduction or elimination of wastes and reduced energy use, and unique solutions for remediation and the treatment of pollutants. However, the potential impact of manufactured nanomaterials used in various applications also needs to be evaluated in the context of human health with regard to potential toxicology and routes of exposure, environmental effects, including fate, transport, transformation, bio‐availability, and bio‐accumulation, and an analysis of product life cycle.
Phase‐Coherent Transport
Authors: Schäpers Thomas
Published: June 2010

In this chapter the essential phenomena of phase‐coherent transport in nanoelectronic structures are discussed. First, the relevant length scales – that is, the elastic mean free path, the inelastic mean free path, or the phase‐coherence length – are defined, and these are subsequently used to classify the ballistic and diffusive transport regimes. Quantized conductance in split‐gate point contacts is discussed as a transport phenomenon in the ballistic regime. The origin of quantized conductance is explained on the basis of the Landauer–Büttiker formalism. The weak localization effect – a transport phenomenon in the diffusive regime – is explained first on the basis of an intuitive picture, but later the exact expressions describing weak localization for different dimensions of the sample are presented and discussed. It will also be demonstrated that the presence of spin‐orbit coupling can result in an enhanced conductivity, opposite to the weak localization effect. Periodic resistance oscillations can be observed in ring‐shaped conductors, and the Al'tshuler–Aronov–Spivak oscillations found in interconnected ring structures are discussed first. For single‐ring structures, the Aharonov–Bohm effect is introduced, which originates from the interference of electron waves propagating along the upper and lower branches of the ring. In very small structures with only a few scattering centers, universal conductance fluctuations are observed; the origin of these fluctuations is explained and their suppression, for example by increasing the temperature, is discussed.
Charge Transport and Single‐Electron Effects in Nanoscale Systems
Authors: Thijssen Joseph M. , van der Zant Herre S.J.
Published: June 2010

In this chapter, single‐electron effects in transport through nanoscale devices are considered. Although these effects are ubiquitous in quantum dot physics, during recent years their observation in molecular transport has triggered important new research efforts. In this case, the experimental results have shown a rich variety of features which enables much information to be extracted regarding the physics of these structures. Most of this information can be obtained in the case where coupling of the active region to the leads is weak, which is in direct contrast to the limits described in Chapter 1 of this volume. It should be noted, however, the richest behavior can be observed precisely on the border of the two regimes – that is, with intermediate coupling. In addition, a very brief outline will be provided of the physics of different transport processes through three‐terminal devices, with subsequent information focused on single‐electron effects.
Spin Injection–Extraction Processes in Metallic and Semiconductor Heterostructures
Authors: Bratkovsky Alexander M.
Published: June 2010

Spintronics is a discipline focusing on phenomena and devices essentially dependent on spin transport. We review recent theoretical and experimental advances in achieving large spin injection efficiency (polarization of current) and accumulated spin polarization. These include tunnel and giant magnetoresistance, (pseudo)spin‐torque and spin–orbit effects on electron transport in various heterostructures. We give a microscopic description of spin tunneling through oxide and modified Schottky barriers between a ferromagnet (FM) and a semiconductor (S). It is shown that in such FM–S junctions electrons with a certain spin projection can be efficiently injected into (or extracted from) S, while electrons with the opposite spin can accumulate in S near the interface. The derived criterion for efficient injection suggests that the barrier should be rather transparent (this is opposite to a criterion in the literature suggesting that it should be opaque). In degenerate semiconductors, extraction of spin can proceed at low temperatures. We mention a few novel spin‐valve ultrafast devices with small dissipated power: a magnetic sensor, a spin transistor, an amplifier, a frequency multiplier, a square‐law detector and a source of polarized radiation. We also discuss effects related to spin–orbital interactions, such as the spin Hall effect (SHE) and a recently predicted positive magnetoresistance accompanying SHE. Some esoteric devices such as ‘spinFET’, interacting spin logic and spin‐based quantum computing are discussed and problems with their realization are highlighted.
Charged‐Particle Lithography
Authors: Berger Lothar , Kretz Johannes , Beyer Dirk , Schwersenz Anatol
Published: June 2010

Although, today, the main method for pattering almost all integrated circuits (ICs) is photolithography, charged‐particle lithography – where charged particles (electrons, ions) are used for patterning – already has a wide range of applications. Electron beam lithography (EBL) is currently utilized for fabricating the photomasks essential for photolithography, as a time‐ and cost‐effective technique for early device and technology development, and also for fabricating the imprint templates necessary for the emerging technique of nanoimprint lithography (NIL). All of these applications are enabled by single‐beam writing techniques, which are undergoing continuous improvement. However, as photomask costs have increased, and continue to increase, it has become almost untenable to produce high‐end ICs in low volume. Hence, today the use of field‐programmable gate arrays (FPGAs) has surpassed that of the faster and more highly integrated application‐specific integrated circuits (ASICs). Consequently, promising new multiple‐beam writing techniques are currently under development, known as maskless lithography (ML2), for the volume production of ICs. Ion beam lithography (IBL) represents an alternative approach for the fabrication of imprint templates for NIL, with the advantage of not requiring resist processing. Currently, both EBL and IBL are the only viable methods for fabricating nano‐electromechanical systems and nanotechnology devices, and therefore are essential tools for the emerging nanotechnology.
Extreme Ultraviolet Lithography
Authors: Bergmann Klaus , Juschkin Larissa , Poprawe Reinhart
Published: June 2010

Extreme ultraviolet (EUV) lithography represents a photon‐based technology for the mass production of semiconductor devices with small feature sizes. It offers the capability of replacing the conventional lithography by defining structural features below 32 nm, and facilitating the further miniaturization of silicon‐based chip technology down to its physical limits. Although the basic physics of the optics is the same as for conventional lithography operating with UV light at a wavelength of 193 nm, the technological step into the EUV range requires changes of all components of the system. This chapter provides an overview of the system architecture of a EUV scanner and the components; that is, the light sources emitting at a wavelength of approximately 13.5 nm, debris mitigation, grazing incidence collectors, multilayer mirrors and the optical system, and also the photo resist. The underlying fundamentals and technological requirements, as well as the current status of development of the essential components, are addressed.
Nanomanipulation with the Atomic Force Microscope
Authors: Requicha Ari
Published: June 2010

Manipulation with scanning probe microscopes has been under development for over a decade, and now provides the capability of building nanostructures automatically, from the bottom up, by assembling nanoscale objects such as particles, rods, and tubes. In this chapter, the current research on nanomanipulation is surveyed, with special emphasis placed on techniques that use the atomic force microscope (AFM) as a robot, the nanoscopic end‐effector of which – the tip – interacts directly with the nanoscale features of the sample. The principles of operation of the AFM, and the spatial uncertainties associated with it, are briefly described. Protocols for moving nano‐objects with the AFM tip are discussed, and experimental results presented which show that AFM manipulation can be used to accurately and reliably position molecular‐sized components. These can then be linked by chemical or physical means to form subassemblies, which in turn can be further manipulated. Interactive AFM manipulation systems are discussed, as well as recent results on automated nanomanipulation.
Harnessing Molecular Biology to the Self‐Assembly of Molecular‐Scale Electronics
Authors: Sivan Uri
Published: June 2010

Some of the remarkable assembly tools provided by molecular biology are harnessed to the construction of functional electronic devices made of inorganic materials. The assembly scheme highlights key ingredients of complex self‐assembly from an algorithmic encoding of information in double stranded DNA templates through recombinant proteins that read the DNA sequence and use it for localizing the electronic components at desired DNA addresses, to metallization of the DNA to form gold wires connecting the components and antibodies that recognize electronic materials. An equivalence between chemical self‐assembly and communication of a message over noisy lines is pointed out and used to introduce a redundancy error suppression scheme from communication for the suppression of DNA synthesis errors.
Formation of Nanostructures by Self‐Assembly
Authors: Homberger Melanie , Karthäuser Silvia , Simon Ulrich , Voigtländer Bert
Published: June 2010

The increasing demands of the semiconductor industry to fabricate nanostructures of only a few nanometers in size has led to an intensified search for alternative nanofabrication methods. One approach is thebottom‐upstrategy, where nanostructures are built up of nanoparticles, molecules, or even atoms. The great challenge to control the nanostructure formation process can be achieved by use of self‐organization methods. In this chapter, selected routes for the fabrication of various nanostructures by self‐assembly processes are described, and details of the underlying basic physical principles are presented. The control over size, shape and composition of the formed nanostructures is an advantage of the methods addressed here, such as the self‐assembly of nanostructures by epitaxial growth, the formation of self‐assembled monolayers, and the formation of nanoparticle assemblies.
Flash‐Type Memories
Authors: Mikolajick Thomas
Published: June 2010

The trend toward more mobile applications drives a rapidly increasing demand for non‐volatile memories. Today, Flash‐type non‐volatile memories offer by far the best trade‐off between cost and performance. In this chapter, Flash concepts relevant to today and the future are reviewed. Following a brief introduction to the market and the history of Flash memories, the basics required to understand the concepts of Flash memory concepts are explained. These mechanisms are involved in charging and discharging the charge storage layer, as well as the architecture used to combine many cells into large memory arrays. The third section details today's mainstream Flash concepts, which are based on the floating‐gate cell, outlines the physics of the floating‐gate transistor, and introduces the concepts of NOR and NAND Flash. Finally, the main reliability‐determining effects are reviewed, and the further scaling path of floating‐gate memories is illustrated. One way of overcoming the limitations of floating‐gate memories is to replace the conductive floating gate with an insulating charge‐trapping layer; hence, the conventional silicon‐oxide‐nitride‐oxide‐silicon (SONOS) cell and its trade‐offs are explained. Multi‐bit charge trapping, a concept recently introduced for both code and data Flash applications is described in detail, and the scaling of charge‐trapping Flash devices is discussed. Finally, a brief introduction is provided to nanocrystal Flash memory devices, which represent another way of overcoming some basic limitations of the floating gate.
Dynamic Random Access Memory
Authors: Horiguchi Fumio
Published: June 2010

In this chapter, we describe the advanced dynamic random access memory (DRAM) concept, its current use, and future challenges. Today, cutting‐edge DRAMs are encountering scaling limitations such as transistor performance degradation and threshold voltage variation. As device scaling advances, memory cell integration encounters difficulties because of the degradation of transistor performance and fine patterning. All these constraints spur interest in a three‐dimensional structural approach to memory device applications. For the DRAM application, trench or stacked capacitors can be used to overcome capacitor area reduction, and an array transistor can be adopted such as the fin‐type double gate or the surrounding gate transistor structure. The new concept of a floating body cell is a one of the most promising candidates for next‐generation DRAMs.
Ferroelectric Random Access Memory
Authors: Park Soon Oh , Bae Byoung Jae , Yoo Dong Chul , Chung U‐In
Published: June 2010

Ferroelectric random access memory (FRAM) has been pursued as the ultimate memory due to its superb properties, such as fast random access in read/write mode and non‐volatility with unlimited usage. However, FRAM has achieved only limited success in low‐density applications because of its large cell size and reliability issues. Recently, highly reliable mega‐bit density scaled FRAMs with 1T1C COB (capacitor over bit line) cell structure have been developed with many key processes and new integration technologies. In order to achieve high‐density stand‐alone memory, it is highly desirable to develop three‐dimensional ferroelectric capacitor technology, where chemical vapor deposition technology is essential for fabricating ferroelectrics as well as electrodes. In this chapter, a brief review is provided of the basic principles of FRAM, and particular attention is paid to the reliability and scalability of high‐density FRAM.
Magnetoresistive Random Access Memory
Authors: Gaidis Michael C.
Published: June 2010

Magnetoresistive random access memory (MRAM) offers the potential of a universal memory, as it can simultaneously be fast, non‐volatile, dense, and show high‐endurance. MRAM differs from earlier incarnations of magnetic memory in that it tightly couples electronic readout with magnetic storage in a compact device structure that is competitive with state‐of‐the‐art semiconductor memories. While small‐scale demonstrations have realized much of the potential of MRAM, shrinking the cell size or embedding the memory with logic circuitry creates difficult challenges. This chapter provides an overview of the basic MRAM magnetic structure, including an explanation of the functions of various elements in the complex multilayer magnetic film stack. The principles of MRAM circuit design and operation are outlined, together with a detailed examination of the design of a single‐bit cell. A discussion of the techniques developed to fabricate large arrays of MRAM devices with high yield is also included, in addition to some aspects of MRAM reliability and the potential for scaling MRAM for future device generations.
Phase‐Change Memories
Authors: Lacaita Andrea L. , Wouters Dirk J.
Published: June 2010

Phase‐change memories (PCM) store their information as the material phase (high‐resistive amorphous, respectively low‐resistive crystalline phase) of a chalcogenide metal alloy, the most important compound being Ge2Sb2Te5(GST). PCM are currently evolving from an interesting new concept to a viable, non‐volatile memory technology that is expected eventually to replace no‐longer‐scaling Flash memory technologies. To provide insight into this important evolution, and why PCM are considered an important technology, this chapter describes their different aspects, commencing with basic operation principles and fundamental material properties. Vital to the operation of PCM are not only the vitrification and crystallization properties of the chalcogenide material, but also the phenomenon of electronic threshold switching, thereby enabling low‐voltage Joule heating in the amorphous phase. The understanding and modeling of these effects are outlined, in addition to cell concepts and aspects of integration technology, including optimization schemes aimed at reducing the program current. Finally, the excellent reliability and scaling properties of PCM are discussed.
Memory Devices Based on Mass Transport in Solid Electrolytes
Authors: Kozicki Michael N. , Mitkova Maria
Published: June 2010

This chapter introduces the concept of low‐energy, non‐volatile memory devices based on mass transport in solid electrolytes. In these devices, information is stored as a change in resistance due to the formation of a metallic filament via the reduction of metal ions in the electrolyte. To show how such elements work, basic solid‐state electrochemistry and ion transport are described, along with the materials science of solid electrolytes, with particular emphasis being placed on the nanostructure of ternary ion conductors. The growth, morphology, and electrical characteristics of metal electrodeposits are discussed and related to both the nature of the materials involved and the operation of memory elements. The configuration and performance of a variety of devices are presented, including factors such as programming speed, endurance, and retention, as well as results that demonstrate physical and electrical scalability of the technology.
Non‐Conventional Complementary Metal‐Oxide‐Semiconductor (CMOS) Devices
Authors: Risch Lothar
Published: June 2010

Silicon complementary metal‐oxide‐semiconductor (CMOS) has been the dominating semiconductor technology for over 20 years such that, today whilst the 90‐nm generation is in production the 70‐nm generation is already under development. Currently, many critical device dimensions have reached 1 to 20 nm, and microelectronics is now on a transition to nanoelectronics. In spite of many roadblocks, the ITRS Roadmap expects that Si‐CMOS can be scaled down to the 22‐nm node during the next 15 years. Besides new materials and strain, non‐conventional MOSFETs with thin silicon channels, multi‐gate and 3d structures have the potential to go beyond the planar MOSFET. Already, several architectures, such as fully depleted SOI, wafer‐bonded double‐gate and FinFET have been demonstrated with promising electrical characteristics at gate lengths of 25 to 10 nm. In fact, quantum mechanical simulations predict that these devices can be functional down to 2 nm gate length. Multi‐gate transistors have also been implemented in high‐density Flash memory cells down to 20 nm, and largeVtshifts suitable for multi‐level storage have been achieved. Similarly, for DRAM 3d cell transistors with low leakage currents will be utilized in future. It seems very unlikely that the Si roadmap will end at the 22‐nm node and, assuming that manufacturing and cost issues can be fulfilled, it is most likely that CMOS will continue to dominate in the era of nanotechnology and gigabit systems.
Single‐Electron Transistor and its Logic Application
Authors: Ono Yukinori , Inokawa Hiroshi , Takahashi Yasuo , Nishiguchi Katsuhiko , Fujiwara Akira
Published: June 2010

The single‐electron transistor (SET) is a three‐terminal device, the electric characteristics of which are governed by the movement of single electrons. The SET's physical size is quite small and its performance, such as ON‐OFF current ratio, improves as its size is reduced. The SET is therefore thought to be a promising device for large‐scale and low‐power integrated circuits. In addition, its current characteristics are unique and much different from those of conventional transistors. This makes the SET one of the best functional devices, and a rich variety of architectures for SET‐based logic circuits have been proposed and experimentally tested. This chapter describes SET research from the viewpoint of logic‐circuit applications.
Magnetic Domain Wall Logic
Authors: Allwood Dan A. , Cowburn Russell PVthVV.
Published: June 2010

Magnetic domain wall logic technology is based upon controlling the magnetization processes in ferromagnetic nanowire circuits. Opposite magnetization directions in the nanowires are used to denote logical “1” and “0”. Switching between these two states is achieved by using applied magnetic fields to propagate magnetic domain walls through the nanowires. Nanowire junctions are used to perform various operations, including logical NOT, logical AND, signal fan‐out and signal cross‐over. A suitable combination of these structures in a digital circuit allows any computation to be performed. Data writing and erasing can also achieved by using additional circuit features and control of the applied magnetic field. To illustrate the potential use of magnetic domain wall logic, a shift register with continuous data recirculation is presented. Finally, the future potential of this nascent technology is discussed, with particular emphasis on non‐volatile serial data storage.
Monolithic and Hybrid Spintronics
Authors: Bandyopadhyay Supriyo
Published: June 2010

“Spintronics” is the science and technology of using the spin degree of freedom of a charge carrier, either singly or in conjunction with the charge, to store, process and/or communicate information. Both, classical and quantum mechanical information can be encoded by spin. In this chapter, “hybrid” and “monolithic” spintronics are discussed; the distinction between the two is that, in the former case, spin is not used directly to store or process information; rather, that role is still delegated to charge. But spin influences
how
charge stores or manipulates information. The role of spin is secondary and may, at best, augment the role of charge. Examples of hybrid spintronic devices are spin field effect transistors (SPINFETs) and spin bipolar junction transistors (SBJTs). It is also noted that hybrid devices are not likely to yield major advances in device engineering in the short term. On the other hand, monolithic spintronics, which deals with devices in which spin single‐handedly stores and processes information, is much better poised to make major advances. An example of this is “single spin logic” (SSL), where a single electron acts as a binary element (two‐state switch), its two orthogonal spin polarizations being used to encode binary bits 0 and 1. Switching between bits is accomplished simply by flipping the spin of the electron, without physically moving charges in space and causing a current flow. In this way energy is saved, leading to a much‐reduced power dissipation. The switching time is also not limited by the speed of charge carriers as there is no charge motion. The
maximum
energy dissipated in SSL gate operation is the Landauer–Shannon limit of
kT
ln(
p
) per operation (where 1/
p
is the error probability). The chapter concludes with a brief discussion of spin‐based quantum computing, where the spin of an electron in a quantum dot is used to implement a qubit. Of note, this last section is necessarily brief and will most likely be outdated by the time this book is printed, as rapid strides are being made in that area.
Organic Transistors
Authors: Klauk Hagen
Published: June 2010

Organic transistors are field‐effect transistors in which the semiconductor is a thin film of a conjugated organic material. As organic semiconductors can often be processed at or near room temperature, this allows the implementation of electronic functionality on large‐area flexible substrates for a variety of emerging applications.
Carbon Nanotubes in Electronics
Authors: Meyyappan M.
Published: June 2010

Carbon nanotubes exhibit unique electronic properties, making them an interesting alternative in logic, memory and other nanodevice applications. An overview of growth and some of these applications is provided in this chapter. Possible near‐term applications in interconnects, chip cooling and metrology in integrated circuit manufacturing are also discussed.
Concepts in Single‐Molecule Electronics
Authors: Lüssem Björn , Bjørnholm Thomas
Published: June 2010

Molecular electronics is an exciting and rapidly evolving field of research. Since the first notion of single‐molecular electronics, an ever‐growing number of possible functional molecules have been proposed. This chapter provides a short overview on the recent development of molecular electronics, beginning with a short theoretical introduction in which the basic concepts and terminology of molecular electronics are explained. Subsequently, several techniques to contact single molecules and to measure the current transport across these molecules are described. There follows a description of various compounds that have been shown to exhibit electronic functionality and possible circuits, and architectures that are suited for molecular electronics are introduced. Finally, a brief overview is provided of the main future challenges of molecular electronics.
Intermolecular‐ and Intramolecular‐Level Logic Devices
Authors: Remacle Françoise , Levine Raphael D.
Published: June 2010

The design is discussed of molecule‐based logic circuits where each action implements much more than a switch. Results to date that have been validated byproof of conceptexperiments including on the one hand the implementation of combinational circuits on a single molecule and, on the other hand, the inter‐ and intra‐molecular communication of the results of logic operations. A complementary and even more powerful design is that of a finite‐state logic machine on a single molecule and beyond that, programming of a single molecule. Both electrical and optical addressing and readout are discussed, the advantage being that it is not necessary to be able to address many states as with three states a full adder can already be achieved. The chapter concludes with some perspectives for the future and a list of desiderata.
Nanowire‐Based Programmable Architectures
Authors: DeHon André
Published: June 2010

Through bottom‐up synthesis techniques it is now possible to construct wires which are just a few atoms in diameter; these wires can be selectively field‐effect gated, and wire crossings can act as diodes with programmable resistance. These new capabilities present both opportunities and challenges for constructing nanoscale computing systems. The tiny feature sizes offer a path to economically scale down to atomic dimensions. However, the associated bottom‐up synthesis techniques produce only highly regular structures and demonstrate high defect rates and minimal control during assembly. In order to exploit these technologies, nanowire‐based architectures have been developed which can bridge between lithographic and atomic‐scale feature sizes and tolerate defective and stochastic assembly of regular arrays to deliver high‐density, universal computing devices. Using 10 nm pitch nanowires, these nanowire‐based programmable architectures offer one to two orders of magnitude greater mapped‐logic density than defect‐free lithographic field‐programmable gate arrays at 22 nm.
Quantum Cellular Automata
Authors: Macucci Massimo
Published: June 2010

The processing of logical information has been based, since the time of the first electromechanical computers, on the paradigm of a three‐terminal device operating as a controlled switch, be it a relay, a vacuum tube, or a transistor. Therefore, although the technology has undergone extraordinary developments in terms of device miniaturization, switching speed, reliability, and power consumption, the basic concept behind circuit design has remained substantially unchanged. A bold departure from this traditional implementation is represented by the quantum cellular automaton (QCA) concept, whereby logic computation is achieved by means of two‐dimensional arrays of bistable cells. In this chapter the advantages and scalability of the QCA approach are discussed, as well as the technological difficulties that so far have impaired any attempt to make this technology suitable for large‐scale production.
Quantum Computation: Principles and Solid‐State Concepts
Authors: Weides Martin , Goldobin Edward
Published: June 2010

In this chapter we review the basics of quantum computation and discuss promising physical systems for implementation of a qubit. The advantage of quantum computation over classical computation is shown by presenting the quantum algorithms for searching databases and factorizing numbers. In addition, quantum bits are ideal candidates for secure communication. The operation scheme and error correction of quantum computation are reviewed. First experimental realization of quantum computation by nuclear magnetic resonance is outlined. Several types of scalable solid‐state qubits based on semiconductors and superconducting Josephson junctions (charge, flux and fractional flux qubits) are presented.
Nanoparticles for Cancer Detection and Therapy
Authors: Godin Biana , Serda Rita E. , Sakamoto Jason , Decuzzi Paolo , Ferrari Mauro
Published: June 2010

The administration of nanovectors, nanoparticles or other systems having nanoscale components, that direct active agents to concentrate preferentially into their target lesion sites, has emerged as a striking treatment option which can improve therapeutic index and or enhance the imaging contrast. The challenge in achieving desired pharmacokinetic, pharmacodynamic and toxicological profiles, is decoupled from the specificin vitrorecognition of a biological target, but is directly related to the presence of numerous biobarriers which all molecular agents or nanovectors should surpass to efficiently reach their destination. For more than a decade, oncology has been occupying the foremost position in nanomedicine, being the area of medicine for which numerous ‘nanodrugs’ are routinely used in the clinical situation. This chapter starts with an introduction to tumor physiology and medicaments currently used in oncology. Later, therapeutic and imaging delivery vectors from a ‘nano‐toolbox’, in clinical use and under various stages of development, are presented. The ‘pros’ and ‘cons’ of these systems for the design of specific, personalized and targeted medications are then critically discussed. The advantages of the nanovectors' rational design to efficiently negotiate biobarriers and various aspects of a preclinical characterization for the nanoscale systems are further argued. The chapter concludes with an outlook on the unresolved issues and opportunities in cancer nanomedicine.
Electron Cryomicroscopy of Molecular Nanomachines and Cells
Authors: Baker Matthew L. , Marsh Michael P. , Chiu Wah
Published: June 2010

Electron cryomicroscopy (cryo‐EM) is an emerging biophysical tool that can be used to determine the structures of molecular nanomachines in fully solvated conformations at subnanometer resolutions (<1 nm). Such cryo‐EM maps can reveal long α‐helices and large β‐sheets. In the highest resolution cryo‐EM density maps, it is possible to see bulky side chains and trace the Cα backbone of molecular subunits within a multicomponent nanomachine. Electron cryotomography (cryo‐ET) is equally powerful because of the unique cellular context in which it can capture and reveal cellular nanomachines. Despite reaching only 4–10 nm resolution, cryo‐ET reconstructions are capable of imaging whole cells and distinguishing their molecular components. Both of these methods are complementary to conventional methods of structure determination, including X‐ray crystallography and NMR spectroscopy. Hybrid methods that combine these structural techniques with cryo‐EM and cryo‐ET result in a complete view of nanomachines from atomic detail to their spatial and temporal location within a cell. This chapter will describe the experimental and computational pipeline in cryo‐EM and cryo‐ET and illustrate their effectiveness with examples from an ion channel, spherical virus, cellular motor and the survey of a complete cell.
Pushing Optical Microscopy to the Limit: From Single‐Molecule Fluorescence Microscopy to Label‐Free Detection and Tracking of Biological Nano‐Objects
Authors: Kukura Philipp , Renn Alois , Sandoghdar Vahid
Published: June 2010

The promise and success of current biomedical research is highly dependent on understanding the mechanisms of fundamental biological processes such as protein folding, the function of molecular machines, or the interaction of proteins with molecular complexes. In particular, on the cellular level the heterogeneous and fluctuating environment as well as the intrinsic asynchronicity of protein function requires observation of individual copies rather than ensembles if a detailed understanding of their function is to be obtained. As a consequence, real‐timein vivoimaging is one of the most desirable tools for investigating biological systems at microscopic and nanoscopic levels. In this chapter, we summarize some of the recent advances in optical microscopy with a particular focus on the capabilities and limitations of studies at the single‐molecule and nanoparticle level. We present a detailed account of the intricate interplay between single‐molecule photophysical properties and the attainable signal‐to‐noise ratio in the ability to see, localize and trace single molecules. Furthermore, we discuss the possibility of single‐molecule labels being replaced by tiny light scatterers, such as gold nanoparticles, which offer an inherent photostability and lack of saturation. In particular, we introduce a novel interferometric technique for detecting nanoscopic objects and demonstrate its potential use both for the study of gold nanoparticle labels in scattering media and the label‐free detection of single biological nanoparticles in the absence of additional scatterers.
High‐Content Analysis of Cytoskeleton Functions by Fluorescent Speckle Microscopy
Authors: Applegate Kathryn T. , Yang Ge , Danuser Gaudenz
Published: June 2010

The development of nanomedical strategies requires precise mechanistic models of cellular pathways. At center stage of many of these pathways is the cytoskeleton, which dynamically organizes cellular architecture and mediates cell morphological functions. In this chapter we review the principles and selected applications of quantitative fluorescent speckle microscopy (qFSM), a combined imaging modality and statistical toolset that delivers high‐resolution measurements of cytoskeleton structure and dynamics in living cells. qFSM has emerged as an invaluable tool in studies aimed at delineating the mechanisms of cytoskeleton regulation by the systematic perturbation of molecular signals upstream of cytoskeleton outputs. Additionally, qFSM can be used as a precise readout of cytoskeleton responses in the search for new drugs and nanomedical strategies that alter cellular behavior by intervening with specific cytoskeleton functions.