They have seen the future, and it is small Nanotechnology leads Rutgers researchers into a new atomic age Archived article from Nov 4, 2002 By Bill Haduch   What is nanotechnology and what promises does it offer? To better understand how and why scientists work at the atomic level, Focus reporter Bill Haduch spent a day with chemistry Professor Eric Garfunkel at the Nanophysics Laboratory on the Busch campus. There are surprises at the border between chemistry and physics: the ability to see, move and use atoms as if they were bricks. Research equipment that looks like it came from Davy Jones' locker. And world-class soccer matches, too. First thing on a clear morning, wavy-haired chemistry Professor Eric Garfunkel strides out of his office in the Wright Chemistry Building on the Busch campus and cuts diagonally across a large, flat, grassy quadrangle toward the Nanophysics Labs. "This is the perfect place for soccer," he says, rattling off some of the nationalities of the students and faculty who play impromptu games here. "Between the chemistry and physics departments we have Russian, Chinese, Turkish, Mexican, English, Italian, Swedish, Argentinian, Romanian and American players. It makes for some pretty exciting match-ups." International soccer skills aside, students from the United States and other countries have brought their talents to Rutgers to study and teach in the new world of nanotechnology, where scientists work atom by atom, imaging, arranging, re-arranging and constructing amazing new materials just as nature does, from the bottom up. They're doing it in chemistry, in physics, in engineering, in biology. In virtually all the sciences, nanotechnology is hot. And because atoms are atoms, sharing equipment, expertise and talent between departments is the rule, not the exception. What is nanotechnology? The term nanotechnology emerged only in the late 1980s. By the late 1990s, the National Science and Technology Council was so impressed by its promise that it predicted nanotechnology's impact on human life will be "at least as significant as the combined influences of antibiotics, the integrated circuit and human-made polymers." "Nano" comes from the measurement unit "nanometer" ¡ª one billionth of a meter, the width of about five to 15 atoms. (For comparison, about five trillion carbon atoms can fit in the period at the end of this sentence.) Working in this realm has been imagined for decades, but it only became practical when humans gained the ability to actually see atoms routinely on all kinds of surfaces at this scale. The breakthrough came in 1981 when the scanning tunneling microscope (STM) was co-invented by Nobel Laureates Gerd Binnig and Heinrich Rohrer of Switzerland. Rohrer had spent a two-year postdoctorate at Rutgers in the early 1960s. Today, Rutgers has five STMs, and this morning Garfunkel is on his way to the Nanophysics Lab of Ted Madey, State of New Jersey Professor of Surface Science and director of the Laboratory for Surface Modification, to look at a new one being fine-tuned by a physics graduate student. The student, Ivan Ermanoski, designed and assembled the machine and is now using it to explore how a single layer of palladium atoms on a tungsten surface can cause formation of nanoscale features. The goal of this project, funded by the Department of Energy and the Army Research Office, is to understand how surface modification at the nanoscale can improve surface reactions involved in petroleum processing. On another STM in the same lab, a chemistry graduate student, Qifei Wu, is exploring formation of nanoscale clusters of nickel and copper atoms. His objective is to help create an inexpensive way to take sulfur pollutants out of petroleum products. "The work we're doing is at the interface between chemistry and physics," says Madey, speaking with the clear precision of a seasoned classroom lecturer. "A physics grad student and a chemistry grad student working in the same lab represents the interdisciplinary nature of nanotechnology." Garfunkel points out that chemists have always worked with atoms ¡ª they just couldn't always see them. He also notes it's not unusual for researchers to design and assemble their own STMs. "Buying a complete state-of-the-art STM off the shelf, with all the bells and whistles, might cost $750,000. Putting it together yourself can save about half, and you get exactly what you want." Garfunkel himself built an STM years ago using an understanding of chemistry, physics and instrumentation gained at Berkeley and during fellowships in China, France, Germany and Italy. He said that as a youth, he developed an appreciation for mechanical things by constantly taking things apart "and sometimes putting them back together." Working in a bicycle shop also helped, he says. Working in a vacuum Today, the new ultrahigh vacuum STM in Madey's lab is the gleaming center of attention. Surrounded by wires, pumps and metal rods, its stainless steel main body is roughly the size and shape of an old-fashioned diving helmet, and it even has portholes that look straight out of "Das Boot." "It does look nautical," says Madey of the table-sized apparatus, "and when you think about it, we're trying to keep air out of it just like a submarine tries to keep out water." The reason for keeping air out of an ultrahigh vacuum STM is simple ¡ª when you want to look at surface atoms, the molecules in the atmosphere can easily get in the way. Creating the vacuum takes about two days of pumping, heating and cooling. "By the time the vacuum is created, the number of remaining reactive molecules compared with the earth's atmosphere is the same ratio as one dollar compared with the gross national product," says Madey, who seems particularly pleased with the quietness and low vibrations of the pumps on the new STM. Before creating the vacuum though, the sample to be studied must be prepared and loaded into the STM. "It's a manual process, and it can take a lot of time," Madey says. A typical experiment, such as the one to remove pollutants from petroleum, might begin with a graduate student slicing a watch battery-sized disk from a tungsten rod with a diamond blade and then patiently polishing the disk for days and days until its surface is as close to perfectly smooth as possible. "We end up polishing with abrasive particles smaller than the wavelength of light," says Madey. The mirrorlike tungsten disk is then slid into the STM through one of its portholes, and the porthole is bolted shut. About two days later, after vacuum creation is complete, it's time to look at the atoms. A magnetic transfer rod system lets researchers work within the STM without destroying the vacuum. Using a tiny filament, the scientist can evaporate atoms of platinum onto the tungsten disk, creating a veneer of platinum on the tungsten one atom thick. "Metals like platinum, palladium and rhodium are very good catalysts for processing petroleum and for removing pollutants from automobile exhausts, but they're very expensive. One of our goals is learning how to optimize their use," says Madey. "A veneer one atom thick is as thin as you can go." Now the STM really goes to work, letting Madey and crew see and study the single layer of pure platinum atoms. Controlled by computer, the STM lowers a probe, somewhat like a phonograph needle, infinitesimally close to the layer. The probe sends a steady stream of electrons "tunneling" through the vacuum to the surface. The stream reaches into the nooks and crannies around the atoms and sends signals to a computer, which creates a detailed topographical map of the surface. The computer can add any choice of color and shading to the display, but in reality there are no colors in the world of atoms. "The images we're seeing are actually smaller than lightwaves," says Garfunkel. "You could not see these images with an optical microscope, no matter how powerful it was." The resulting image, pictured in shades of red added by the computer, seems covered in smudgy bright circles and rows of symmetrical pyramids. Madey says the bright areas are the actual atoms. "A surprising thing happens when you put that layer of platinum on a heated tungsten surface," he says. "All these little pyramids or facets grow, and the reactivity changes. They're the same atoms, but now they're arranged differently and the chemical activity changes. That's the main point of this experiment ¡ª to try to learn how changing the surface structure changes the chemistry." Thin chips After checking out the new STM, Garfunkel heads across the hall to a large lab he shares with physics Professor Torgny Gustafsson. This is the headquarters of their current work ¡ª studying thin dielectric films that can be used in future generations of computer chips. And when he says thin, he's talking a few atoms thin. "We're at a point where computer chips can't get much smaller using current technology," Garfunkel says. "We need to get down to the atomic level if we're going to continue putting more memory on smaller chips." Garfunkel and Gustafsson use one of the nation's only medium-energy ion scattering accelerators to carry out their work. Looking something like a giant STM, it fills the better part of a large room. Ion particles at 100,000 electron volts stream into the device from a long accelerator tube and slam into a thin film sample in a vacuum chamber. The scientists then use detectors and computers to analyze what bounces back from the sample. They can tell what atoms the ions hit and how deeply into the film they penetrated. "We can determine the composition of these thin films better than anyone else can," Gustafsson explains in his light Swedish accent. "We're mostly doing basic science, telling people how to create better films and what kind of properties to expect from these films." The information is valuable to industry, and Garfunkel and Gustafsson's work is funded by the National Science Foundation and the Semi-conductor Research Corporation, a consortium consisting of IBM, Intel, TI and Motorola. "Companies need to focus more on the short-term, applying science to actual products," says Garfunkel. "Here we are focusing on technologies that will be used five to 10 years out." Cutting back across the field to the Wright Chemistry Labs, Garfunkel speaks of the freedom he feels working at Rutgers. "I might be working on a technological goal like a better chip, but if I find some new basic thing, I can study it. We have enormous freedom to do that as faculty members. It's not like a company where we have to make this product or that product." Garfunkel, Madey, Gustafsson and their colleagues are part of the New Jersey Commission on Higher Education Work Excellence Program on Nano-materials Science and Engineering, headed by Professors Stephen C. Danforth and Lisa Klein of ceramic and materials engineering. It's not the same old NPL Rutgers' commitment to nanotechnology was underscored last fall when the Nuclear Physics Laboratory was renamed the Nanophysics Laboratory. A relic of the atomic age of 40 years ago, the facility was built with earthen embankments on three sides and a 2- to 3-foot layer of earth on the roof. You can't be too careful when you're firing up an 8-million-volt tandem accelerator to shoot atomic particles into targets to watch what happens. Today, the giant accelerator has been removed and the building has been totally renovated to provide offices and lab space for faculty and postdocs associated with Professor Ted Madey's Laboratory for Surface Modification, as well as other condensed-matter laboratories. Inside, the thick concrete walls and concrete-plugged storage tubes that once held nuclear materials still speak of Cold War-era research, but the labs now hold scanning tunneling microscopes, atomic force microscopes and other equipment that Khrushchev never heard of. Scientists still work with atoms here, because nanotechnology is ultimately all about seeing, moving and building with atoms. And the heavy construction still serves a purpose, too. In the nanoworld, the vibration from a footstep can be like an earthquake, wrecking a scan that took days to set up. The Nanophysics Laboratory provides a place for nano-study that's as solid as a rock. "Plus," jokes Madey, "changing it from Nuclear Physics Lab to Nanophysics Labs didn't require changing the acronym. It was and still is NPL." ¡ª Bill Haduch

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