SYDNEY scientists have built the world's tiniest transistor by precisely positioning a single phosphorus atom in a silicon crystal.
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The nano device is an important step in the development of quantum computers – super-powerful devices that will use the weird quantum properties of atoms to perform calculations billions of times faster than today's computers.
Michelle Simmons, of the University of NSW, said single atom devices had only been made before by chance and their margin of error for placement of the atom was about 10 nanometres, which affected performance.
Her team was the first to be able to manipulate individual atoms with "exquisite precision".
Using a technique involving a scanning tunnelling microscope, they were able to replace one silicon atom from a group of six with one phosphorus atom, achieving a placement accuracy of better than half a nanometre. "This device is perfect," Professor Simmons, director of the Australian Centre of Excellence for Quantum Computation and Communication Technology, said.
The single atom sits between two pairs of electrodes, one about 20 nanometres apart, the other about 100 nanometres apart.
When voltages were applied across the electrodes, the nano device worked like a transistor, a device that can amplify and switch electronic signals.
The research is published today in the journal Nature Nanotechnology.
First developed in the 1950s, transistors revolutionised the electronics industry.
Since then, miniaturisation has seen the number of transistors squeezed onto a circuit double about every two years – a trend known as Moore's law.
Professor Simmons said this led to the prediction that transistors would need to reach the single atom level by 2020.
"So we decided 10 years ago to start this program to try and make single atom devices as fast as we could, and try and beat that law."
This had now been achieved eight to ten years ahead of the industry's schedule, she said.
Last year, Professor Simmons was named NSW Scientist of the Year for her team's research.
About 15 to 20 years of research is needed before quantum computers become widely available.
Researchers at Purdue University in the US, the University of Sydney, the University of Melbourne and the Korea Institute of Science and Technology Information in Daejeon were also involved in the research.
Deborah Smith is The Sydney Morning Herald's science editor.
