The single atom transistor: how they did it

Physicists have just created a working transistor out of a tiny phosphorous atom placed within atomic scale electrodes all within a silicon crystal. It's the precision with which the atom and the other constructs are placed that is key to this breakthrough.

Previously single atom transistors only been achieved by chance or fine tuning multi-atom devices — and when the positioning is off even by ten nanometers it is enough to create operational slow down.

So how did scientists get this to finally work so precisely?

Scientists from the ARC Centre for Quantum Computation and Communication at the University of New South Wales in Australia used a scanning tunneling microscope (STM) to see and manipulate atoms on the surface of the crystal while inside an ultra-high vacuum chamber.

First the team started with placing the phosphorus atoms on the surface of the silicon crystal in precise functional patterns. They covered this with a layer of non-reactive hydrogen and then removed select sections with the STM. Phosphorus atoms were then deposited in the selected areas and then an additional layer of silicon is added.

The microscopic device even has tiny visible markers etched onto its surface so researchers can connect metal contacts and apply a voltage, says research fellow and lead author Dr Martin Fuechsle from UNSW via Eureka Alert.

According to the scientists, the properties exhibited by the single atom transistor are in line with theoretical predictions for the device modeled at Purdue University and University of Melbourne.

It has been predicted that transistors would reach the single atom level by 2020 in keeping with Moore's Law — which is an equation based on computing trends that indicates the number of chip components will double every 18 months. Given this leap towards being able to accurately create a single atom transistor, it is likely to accelerate this future of quantum computing to an earlier date.

The results of the research were detailed in a paper published in the journal Nature Nanotechnology. The team included the University of New South Wales, and the paper was completed along with Purdue University and the University of Melbourne.

EurekaAlert, via ABC.net.au

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