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Physicists Win Nobel for Tech Advances
10 October 2000 7:00 pm
This year's Nobel Prize in physics might as well be made out of silicon instead of gold. For it was with silicon that the three recipients--Jack Kilby of Texas Instruments in Dallas; Herbert Kroemer of the University of California, Santa Barbara; and Zhores Alferov of the A. F. Ioffe Physico-Technical Institute in St. Petersburg, Russia--made their crowning achievements. Computers, cell phones, and CD players rely on technology they made possible.
Silicon technology has come a long way. In late 1947, scientists at Bell Labs invented the transistor, ushering in the computer age. John Bardeen, Walter Brattain, and William Shockley won the 1956 Nobel Prize for the invention, but their transistor was not ideal. Though it was much smaller and more reliable than the vacuum tubes it replaced, manufacturers still had to solder thousands of transistors and other components to a circuit board for even the most rudimentary computers. "By that time people could visualize electronic equipment that couldn't be built--it was too expensive, too bulky, and too unreliable," Kilby recalls.
In 1958, Kilby came up with a solution: Put all the components of a circuit on a single wafer of semiconducting crystal such as germanium or silicon. Kilby carved transistors, resistors, condensers, and other elements on the same wafer and out of the same materials, all layered and wired on one crystal. This "integrated circuit" avoided the labor problems, space constraints, and quality control issues that plagued a circuit board with individual transistors. Kilby and a competitor, the late Robert Noyce of Intel, are credited with inventing the integrated circuit that put the computer revolution in high gear.
Kroemer won his Nobel for a refinement of the basic transistor that made it faster and more efficient. The so-called heterojunction bipolar transistor uses two complementary semiconductors (such as gallium arsenide with aluminum gallium arsenide) where traditional transistors used just one (such as silicon). Kroemer realized he could increase the transistor's efficiency and tailor its properties by altering the structures and materials of the two layers. Kroemer and Alferov also demonstrated a way to induce heterojunction semiconductors to emit laser light of various frequencies.
Kroemer and Alferov's brainstorm led to the development of radio satellites, base stations for mobile phones, fiber-optic cables, and CD players, notes semiconductor laser researcher Al Cho of Bell Labs in Murray Hill, New Jersey. "I think they certainly are pioneers."