Nanotechnology

The Big World of Small

Nanotechnology is a term that encompasses scientific and engineering activities at the nanometer scale. A nanometer is one billionth of a meter, or only a few atoms long. Using an array of ultra-precise tools, scientists can create electric components and machines that are virtually invisible to the naked eye. Even genetic engineering and bioremediation, the use of microbes to eliminate hazardous wastes, fall under the broad definition of nanotechnology.

This is not science fiction but science fact. Two years have passed since IBM scientists spelled out their company logo by moving 35 xenon atoms with a device called a scanning- tunneling microscope. Yet in that short time, nanotechnology has demonstrated the potential to become an important, pervasive technology. Today, for example, microsensors tinier than the width of a human hair are routinely being used in automobile anti-lock braking systems.

Georgia Tech Is Thinking Small

Dr. Richard Higgins, director of Georgia Tech's Microelectronics Research Center (MRC) and one of the leaders of the Institute's nanotechnology movement, groups most nanotechnology research into three areas: modeling, measuring and making.

Tech is involved in all three.

The scanning-tunneling microscope is one of the workhorses of nanotechnology, and the progenitor of all other atomic imaging devices. Developed in the early 1980s, it was the first device to actually provide pictures of atoms. It can also move individual atoms and molecules.

Dr. Phillip First of the School of Physics and the MRC has used the instrument to make and measure novel nanostructure-like "wires" a mere two atoms wide. The problem is that such "wires" can't carry electricity like normal wires; they are so small that classical rules of physics break down and quantum mechanics effects take over.

Dr. Thomas Gaylord, Dr. Kevin Brennan, and Dr. Elias Glytsis of the School of Electrical Engineering and the MRC have figured out how to turn quantum mechanical disadvantages into incredible advantages, which they believe will lead to a revolutionary new class of semiconductor devices using "electron-wave optics." These devices would be smaller, faster and less expensive than anything currently on the market.

This development has profound implications. The growth of the $70 billion microelectronics industry has been predicated on making computers smaller and smaller, which has been done by putting as many integrated circuits and transistors as possible on a microchip. (An Intel 486 microchip contains about 1.2 million components.)

The semiconductor industry is fast approaching a size limit beyond which quantum mechanics will not allow conventional electronics to work. The reason is that at about 0.25 micrometers, electrons start behaving like waves. But by using electron-optics techniques, the 0.25 micrometer "barrier" can be broken, allowing "ultraminiaturization down to the atomic scale," says Gaylord.

This will mean new growth in electronics, computers and manufacturing industries, and could even lead to an entirely new industry--nanoelectronics, he says.

Chip-size Computers

Cheaper and more versatile than conventional lasers, the devices "will be able to replace lasers the size of an entire table with lasers the size of a grain of salt," Gaylord says. "People have been working with lasers for over 20 years, but no one has ever thought of this approach."

Another result of Gaylord's work is "guided electron-wave integrated circuits." This would be the next generation in integrated circuits--"a multi-billion-dollar industry," he says. With this technology, you could have "a powerful computer on a single quantum semiconductor chip."

Tech physicist Dr. Uzi Landman's work with colleague Dr. David Luedtke in molecular modeling has made them recognized leaders in the field. Using a Cray supercomputer, they have produced computer-simulated "videos" of atomic interaction showing how a scanning-tunneling microscope can induce gold atoms to "jump" across nanometers of space to coat a probe. These videos help scientists understand friction forces between unlubricated metals.

Micromachines and Micromotors

Allen's biggest challenges involve merging the mechanical microstructure with microcircuitry, developing new fabrication processes and developing new materials to advance the state of the art. Allen, working with PhD graduate students Chong Ahn and Yong Kim, has made the world's first magnetic microinductor and magnetic micromotor. Previous micromachines used electrostatic energy, but magnetic micrometers hold the potential to be much stronger, more durable and more versatile. Allen stresses that what he is doing is not nanotechnology in the strictest sense--his micromachines are still gargantuan on an atomic scale. However, it is a major step in the "small" direction.

Also at the Microelectronics Research Center, Dr. Kevin Martin and Ph.D. candidate M. A. Maldonado use a technique called electron-beam lithography to cut and fashion nanoscale devices. Examples of devices they have fabricated include the world's smallest picture of Buzz, drawn with lines only a few nanometers wide; one-dimensional quantum wires for carrying electrons; zero-dimensional quantum dots; and electron turnstiles.

Martin and his associates do much of their work in the center's clean-room fabrication complex. In the same facility, Dr. Paul Kohl and PhD candidate Kirkland Voght of the School of Chemical Engineering use a process called chemical-vapor deposition to improve integrated circuits and semiconductors used in computers and electronics.

Work on nanotechnology is steadily progressing at other uni versities and laboratories in the U.S. The University of California at Berkeley and the National Nanofabrication Facility at Comell are leading the way in developing many new techniques. Scientists at the University of California-Irvine have fabricated a battery only one-l00th the size of a red blood cell. At the Massachusetts Institute of Technology, Dr. Julius Revok Jr. has fashioned a molecule that can self-replicate, or copy itself. DuPont scientists have designed a protein that can fold predictably. The world is getting smaller and smaller.

Japan's Small Priority

Japanese government and industry have teamed together to fund a number of nanotechnology projects through the Exploratory Research in Advanced Technology (ERATO) program. The program funds groups of 15 to 20 researchers with up to $3 million per year to work on efforts such as:

• The Yoshida Nanomechanism Project, which is focused on furthering microengineering technology.

• The Aono Atomcraft Project, which explores ways to move and bond atoms to create new materials.

• The Hotani Molecular Dynamics Assembly Project, which is concerned with molecular self- assembly and production of "intelligent" materials.

The Japanese Ministry of International Trade and Industry encourages similar efforts at universities and research centers across the the country. Kyoto University now has a Department of Molecular Engineering, and Tokyo Tech is tackling nanoscience through its recently restructured interdisciplinary programs.

The bottom line is that if the U.S. fails to pursue aggressively its own lines of research in nanotechnology, it could very well become a pauper in the technological New World Order.

Prophet and Pitfalls

Nanotechnology will even be able to "build up and restructure tissue" and "eliminate viruses from the body," he says. "Even missing teeth could be regrown."

Skeptical? You have plenty of company. Even though nanotechnology of some sort seems destined to become reality, Drexler goes too far for many of his colleagues.

"It's difficult to imagine. Somehow, I can't see it," says Georgia Tech's Martin of Drexler's radical predictions. Drexler is "overly optimistic," agrees Dr. Mark Allen, "but you never know."