Both economic and general physics considerations indicate that the scaling era of the CMOS integrated circuit will begin to saturate around the year 2010. However, fundamental physical laws also indicate that it should be possible to compute at least a billion times faster than present speeds with the expenditure of only one Watt of electrical power. Thus, the age of computation hasn’t really begun yet. There is a tremendous incentive to invent new types of electronic devices and circuits that will have dimensions of the order of nanometers and operate using quantum mechanical principles. In addition, new fabrication techniques will be required that can inexpensively make and connect these devices in vast quantities. The challenge is equivalent to that faced by the inventors of both the transistor and the integrated circuit, who replaced the existing vacuum-tube and wiring technologies with solid-state switches and lithographic fabrication. There are two lines of research that are relevant to future computational systems: the development of a quantum-state switch and the capability to design a system that will assemble itself once the discrete components have been mixed together. In order to satisfy both constraints simultaneously, teams of researchers with backgrounds in physics, chemistry and computer architecture need to work together. One recent proposal for the construction of a nanocomputer involves the explicit incorporation of defect tolerance, which is the capability to operate perfectly even in the presence of manufacturing mistakes in the circuit, into the design of the system. An example of such a defect-tolerant computer was built at Hewlett-Packard Laboratories with current Si technology. The Teramac experimental supercomputer was constructed with specially designed chips called Field-Programmable Gate Arrays. Teramac replaced logic with memory whenever possible and relied on sophisticated computer algorithms to identify and route around the defects in the circuitry in order to realize a significant saving in the cost of its construction. This architecture is currently being explored as the basis for nanocomputers.
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R. Stanley Williams is Principal Laboratory Scientist and Director of the Quantum Structures Research Initiative (QSRI), the basic research department in physical sciences at Hewlett-Packard Laboratories in Palo Alto, California. The QSRI was founded in July 1995 to prepare HP for the major challenges and opportunities ahead in device technology as features continue to shrink to the nanometer size scale, where quantum mechanics becomes important.
Dr. Williams attended Rice University from 1970-74, where he obtained his B. A. degree in Chemical Physics. He attended the University of California Berkeley from 1974-1978, where he obtained his M. S. and Ph.D. degrees in Physical Chemistry. From 1978-80, he was a Member of Technical Staff at AT&T Bell Laboratories. He moved to the University of California Los Angeles as an Assistant Professor in the Department of Chemistry, and was promoted to Associate Professor in 1984 and Professor in 1986. He has received awards for scientific and academic achievement, including the Dreyfus Teacher-Scholar Award and the Sloan Foundation Fellowship. He has been a consultant to several corporations and law firms, as well as an inaugural member of the Defense Science Study Group, an advisor to the Defense Science Board, and an advisor to the Frontier Research Program at the Institute for Physics and Chemistry Research (RIKEN) in Japan. He moved to HP in 1995 as the founding director of the QSRI.
Dr. Williams’ current research interests are in the areas where solid state chemistry and physics overlap with information technology. He started his career as a surface scientist, and contributed to the development of research tools for understanding the physics and chemistry of solid surfaces, such as photoelectron spectroscopy, ion scattering spectroscopy, and scanning tunneling microscopy. He is also one of the early contributors to the chemistry of opto-electronic materials, which involves the synthesis of new materials with desirable optical and/or electronic properties and the fabrication of these materials into useful structures. His most recent research has been in the areas of the production, characterization and processing of nanostructures. These are such small solid materials that their size and shape are as important as composition in determining their properties because of quantum confinement effects.
Representative Publications:
“Shape Transition of Germanium Nanocrystals on a Silicon (001) Surface from Pyramids to Domes,” G. Medeiros-Ribeiro, A. M. Bratkovski, T. I. Kamins, D. A. A. Ohlberg and R. S. Williams, Science 279 (1998) pp. 353-355.
“Equilibrium Shape Diagram for Strained Ge Nanocrystals on Si (001),” R. S. Williams, G. Medeiros-Ribeiro, T. I. Kamins, and D. A. A. Ohlberg, J. Phys. Chem. B 102 (1998) pp. 9605-9609.
“A Defect-Tolerant Computer Architecture: Opportunities for Nanotechnology,” J. R. Heath, P. J. Kuekes, G. S. Snider and R. S. Williams, Science 280 (1998) pp. 1716-1721.
“Computing in the 21st Century: Nanocircuitry, Defect Tolerance and Quantum Logic,” R. S. Williams, Phil. Trans. R. Soc. Lond. A 356 (1998) pp. 1783-1791.
| JST | What Physicists Do | 1999-01-19 |