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NANOTECHNOLOGY the ability to characterize nanoscale structures in three dimensions, (2) the ability to acquire nanoscale data in a timeframe that supports timely and correct interpretations of the results, (3) the ability to measure complex structures with nanoscale compositional heterogeneity, and (4) the ability to establish the dispersion of materials used in nanoscale contacts. Research is required to extend the capabilities to the upper theoretical limits of what can be realized in terms of spatial resolution, chemical sensitivity, speed of data acquisition, and signal-tonoise ratios. Adequate measurements at these length scales have not been done and much needs to be learned about specimen-electron beam interactions. For example, the development and installation of aberration-corrected lenses for the SEM is anticipated have a positive effect on resolution and complex structural characterization abilities. Figure 2 shows the capabilities of aberration-corrected SEM instrumentation used in research. EXAMPLE 3: SINGLE MOLECULE JUNCTIONS The Need The basic idea in molecular electronics is using specially designed single molecules or larger molecular building blocks like carbon nanotubes to provide electronic functions in nanoelectronic devices. In contrast to integrated nanoscale contacts fabricated by top-down wafer-based processes, contacts to molecules are manufactured by bottom-up growing and assembling processes based on individual contacts. The development of products based on molecular electronics devices requires precise control of growing and selfassembling mechanisms as well as a deep understanding of the charge transfer from bulk electrodes to the molecule or molecular building block and the charge transport through the molecule or molecular building block itself. The Challenge Worldwide effort is ongoing to understand on a theoretical and experimental basis, the charge transport in molecules and molecular building blocks as well as the charge transfer to metallic electrodes. Nevertheless, today the methods to derive basic properties from experimental measurements, theoretical models, and computer simulations are not standardized, so the comparisons of results are difficult. These difficulties occur in part from the design and controlled fabrication of the molecules, the molecular building blocks themselves, and the contacts to the outer circuit. The challenge is the development of a standard systematic approach to classify contacts and related characterization methods. Figure 3 illustrates a single-molecule junction formed by binding benzene directly to platinum metal electrodes. Figure 3: A benzene molecule junction spans platinum atomic point contacts. Figure from L. Venkataraman, Viewpoint—Benzene provides the missing link in molecular junctions, Physics 1, 5 (2008) at http://physics.aps.org/articles/v1/5 http:// dx.doi.org/10.1103/Physics.1.5 Reprinted with American Physical Society permission from Physics, 1, 5 (2008); illustration by Alan Stonebraker. Conclusion An optimum way to address the many challenges and questions summarized here is to tap the collective wisdom of participating IEC national committees and other invited international technical experts to develop a consensus on how best to begin. In 2008, IEC TC 113 started a series of workshops regarding nanoscale contacts to begin building an international agreement on action plans. The results of the workshops will be published in an IEC Technical Report. In light of limited available resources, the task group responsible for the report can be the forum for determining which among the many instrumentation and theoretical approaches for eventual high-volume manufacturing of nanoscale contacts are of highest priority. ei Th is article is a contribution of the U. S. National Institute of Standards and Technology, not subject to copyright. All views expressed in this article are those of the author and of others to whom attribution is given and are not necessarily those of the NIST nor of any of the institutions cited therein. Certain commercial equipment, instruments, methods, or materials are identified in this article only to specify experimental or theoretical procedures. Such identification does not imply recommendation by any of the host institutions of the authors, nor does it imply that the equipment or materials are necessarily the best available for the intended purpose. Figure 2: High-resolution observation of gold particles on carbon. (a) before and (b) after aberration correction. Figure from Microelectronic Engineering, Volume 86, Issues 4-6, April-June 2009, Takeshi Kawasaki, Tomonori Nakano, and Kotoko Hirose, Developing an aberration-corrected Schottky emission SEM and method for measuring aberration, Pages 1017-1020, MNE ’08 - 34th International Conference on Micro- and Nano-Engineering (MNE), Copyright 2009. Reprinted with permission from Elsevier. August 09 • NEMA electroindustry 9

August 09 ElectroIndustry

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