Nanotubes Nanomaterials and Nanomaterial Processing

In the past few years, nanotechnology research has been carried out in the context of understanding and developing of nanoscale molecular assemblies and related new products. Nanostructures have attracted considerable attention of late because of their prominent properties, and their applications to novel devices that have advanced features have been studied and planned. While the scale may be small, the number of atoms in these assemblies can be large. Nanomaterials' features depend on quantum effects and typically involve movement of a small number of electrons to support specific usable actions and phenomena. The previous chapters (and Appendices A through F) provided some (but in no way, all) of the basic science for nanotech-nology at the physics and chemistry level. From this chapter forward we concentrate on nanotechnology per se from an engineering and applications point of view. The theory provided in Chapters 2 and 3 and Appendices D and E is routinely employed by nanotechnology researchers to study, develop, and explain the behavior of nanostructures; however, we will not utilize the mathematics of quantum theory in the chapters that follow but sensitize the reader at this juncture that such methods are fundamental to any understanding and/or advancements in this field. The reader should generally be able to follow this material, and the material that follows, even if he or she skipped some portions of the previous chapters and/or appendices.

At a basic stage, nanotechnology requires an understanding of elemental carbon materials on an atomic level. The following list identifies some areas of research and development (R&D) interest: carbon nanostructures (e.g., carbon molecules, carbon clusters, and carbon nanotubes), bulk nanostructured materials, nanofabrication techniques (e.g., nanoimprint, soft lithography, scanning probe microscopy, and traditional lithography), self-assembly methods, nanostructured ferromagnetism, and organic compounds and polymers. Nanomaterials come in all shapes and sizes: They can range from small molecules to complex composites and mixtures [92]. The mechanical, thermal, and electrical properties of carbon nanostructures allow a wide gamut of applications. Besides carbon there are other elements that are beginning to be important as

Nanotechnology Applications to Telecommunications and Networking, By Daniel Minoli Copyright © 2006 John Wiley & Sons, Inc.

nanostructures; this chapter, however, generally only provides an overview of carbon structures, such as fullerenes and nanotubes.

It is worth noting that there are R&D efforts underway to integrate nanoscience and electronics. From an electronic switching perspective, nanotechnology devices operate faster than larger mesoscopic components (the mesoscopic scale ranges from 10 to 10,000nm, that is, 0.01-10 |im). Today's computers use conventional electronics that require costly fabrication techniques; molecular electronics has the potential to shrink devices to the nanoscale with improvements in the power consumption and speed profiles. Techniques have already been developed for the production of structures on a molecular level by suitable sequences of chemical reactions or lithographic techniques (e.g., the latter allows one to manipulate individual atoms on surfaces using a variant of the atomic force microscope*). These and other techniques have been used to manufacture, for example, high-density data storage devices. One is also interested in developing nanocomputers: computers whose fundamental components measure only a few nanometers in size; at press time state-of-the-art computer components are no smaller than about 40-100 nm. Researchers believe that nanoscale devices may lead to computer chips with billions of transistors, instead of millions—which is the range in today's semiconductor technology [93, 94, 95]. This may eventually allow one to develop quantum computers. Quantum computers and memory devices are expected to have applications in cryptography and information technology within a few years [45, 96]. These applications will be explored in Chapter 5 (nanophotonics) and Chapter 6 (nanoelectronics).

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