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New York • Scientists have taken a first early step toward escaping the limits of a technological principle called Moore's Law by creating a working transistor using a single phosphorus atom.
The atom was etched into a silicon bed with "gates" to control electrical flow and metallic contacts to apply voltage, researchers reported in the journal Nature Nanotechnology. It is the first such device to be precisely positioned using a repeatable technology, they said, and may one day help ease the way toward creation of a quantum computer that would be significantly smaller and faster than existing technology.
Moore's law states that the number of transistors that can be placed on an integrated circuit doubles every 18 months to two years, and it's predicted to reach its limit with existing technology in 2020. Cutting the size of a transistor to a single atom may defeat that concept.
"We really decided 10 years ago to start this program to try and make single-atom devices as fast as we could, and beat that law," said Michelle Simmons, director of ARC Center for Quantum Computation and Communication Technology at the University of New South Wales, Australia. "So here we are in 2012, and we've made a single-atom transistor roughly 8 to 10 years ahead of where the industry is going to be."
Moore's Law is named for Gordon Moore, co-founder of Intel Corp., the world's largest chipmaker, who first described the phenomenon in a 1965 report that was later cited by others.
There is a limitation to the latest finding: The atom must be kept at minus-391 degrees Fahrenheit to keep it from migrating out of its channel, researchers said, so the result should be seen as a proof of principle rather than an initial step in a manufacturing process.
"These results demonstrate that single-atom devices can in principle be built and controlled with atomically thin wires, where the active component represents the ultimate physical limit of Moore's Law," the researchers wrote in the report.
Simmons's group, which included scientists from the University of Melbourne and Purdue University in West Lafayette, Ind., isn't the first to create a single-atom transistor. Previous efforts, though, came about as the result of chance and carried a significant margin of error, the researchers said.
The New South Wales scientists used a device called a scanning tunneling microscope to manipulate the atoms on the surface of the crystal in a way that allowed them to precisely pair one up with the electrode needed to control it.
"If you want to make a practical computer in the long term, you need to be able to put lots of individual atoms in," Simmons said in a video. "And there you find that the separation of the atoms is quite critical."
Quantum computers would operate by controlling the movement of electrons in an atom. While the latest finding brings science closer to determining whether quantum computing may be successful at a large-scale level, it remains an open question.