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SCRATCHING THE SURFACE: RESEARCHERS REVEAL INSIGHTS ON SILICON SEMICONDUCTORS
30 September 2005 - University of Wisconsin-Madison
| "Smaller. Faster. Wildly complex." This could easily be the motto for semiconductors-the materials that, among lots of other advances in electronics, allow cell phones to continuously shrink in size while increasing the number of their mind-boggling functions. |
While exceptionally tiny, semiconductors possess the ability to enable a multitude of complex functions, making them an invaluable ingredient in electronics technology. But, while the computer age is in full bloom, knowledge of semiconductor nanostructures is still relatively young; and research seeking to answer essential and sometimes-basic materials questions is occurring at breakneck speed. As part of this race to understand semiconductors better, a team of researchers from the University of Wisconsin-Madison has revealed valuable information about silicon and it's surface structure. In particular, the researchers, who did much of their work at the Synchrotron Radiation Center, examined the inimitable 7 x 7 surface structure of Si(111), the most stable surface of silicon. "Surfaces and interfaces dominate in today's silicon devices, since the surface to volume ratio goes up in small structures. These two-dimensional structures are difficult to study, and the SRC work explores an aspect that has remained unexplored on semiconductors so far," says physicist Ingo Barke, who, along with UW-Madison collaborators, published results in a June 2006 issue of Physical Review Letters. "Our results reveal a very unusual surface band structure, which can be best explained by a mechanism called 'electron-phonon interaction,'" Barke continues. "Phonons are vibrations of the atoms, which are surrounded by electrons. By shaking the surface atoms the orbiting electrons 'feel' these vibrations and change their movement in a characteristic way. Our work connects two intensively studied fields: electron-phonon interaction which causes conventional superconductivity, and semiconductor surfaces which are of great importance for electronic devices and semiconductor technology." While similar research has been done on metal surfaces, the current study is the first example of such examination on a semiconductor surface. History has shown that these interesting jumps in basic knowledge about materials such as semiconductors can have significant practical impacts down the road-and this is particularly true in the case of silicon, which itself has become so inextricably important in modern society that it is credited with its own "silicon age." "Electron-phonon interaction itself is of great scientific and practical interest because it is the key mechanism for conventional superconductivity," Barke notes, adding that the ultimate goal lies in the possibility of tailoring materials for a new generation of "designer superconductors."
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About: University of Wisconsin-Madison
In achievement and prestige, the University of Wisconsin-Madison has long been recognized as one of America’s great universities. A public, land-grant institution, UW-Madison offers a complete spectrum of liberal arts studies, professional programs and student activities. Many of its programs are hailed as world leaders in instruction, research and public service.The university traces its roots to a clause in the Wisconsin Constitution, which decreed that the state should have a prominent public university. In 1848, Nelson Dewey, Wisconsin’s first governor, signed the act that formally created the university, and its first class, with 17 students, met in a Madison school building on February 5, 1849. From those humble beginnings, the university has grown into a large, diverse community, with about 40,000 students enrolled each year. These students represent every state in the nation, as well as countries from around the globe, making for a truly international population. UW-Madison is the oldest and largest campus in the University of Wisconsin System, a statewide network of 13 comprehensive universities, 13 freshman-sophomore transfer colleges and an extension service. One of two doctorate-granting universities in the system, UW-Madison’s specific mission is to provide "a learning environment in which faculty, staff and students can discover, examine critically, preserve and transmit the knowledge, wisdom and values that will help insure the survival of this and future generations and improve the quality of life for all." The university achieves these ends through innovative programs of research, teaching and public service. Throughout its history, UW-Madison has sought to bring the power of learning into the daily lives of its students through innovations such as residential learning communities and service-learning opportunities. Students also participate freely in research, which has led to life-improving inventions from more fuel-efficient engines to cutting-edge genetic therapies. Students, faculty and staff are motivated by a tradition known as the "Wisconsin Idea," described by UW President Charles Van Hise in 1904 as the compelling need to carry "the beneficent influence of the university ... to every home in the state." The Wisconsin Idea permeates the university’s work and helps forge close working relationships among university faculty and students and the state’s industries and government. |
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