“Perfect” single-atom transistor created. ...

“Perfect” single-atom transistor created.

Researchers at an Australian University have created a working transistor out of a single atom of phosphorus, placed on a silicon crystal. The microscopic device even has tiny visible markers etched onto its surface so researchers can connect metal contacts and apply a voltage.

The result - published here - is a huge step towards future quantum computers able to process complex equations which are so far beyond the reach of even the fastest supercomputers. The research will also enable the continuation of ever smaller transistors in accordance with (or even exceeding) Moores Law, which would mean that all transistors reach single-atom level by 2020.

The UNSW team used a scanning tunnelling microscope (STM) to see and manipulate atoms at the surface of the crystal inside an ultra-high vacuum chamber. Using a lithographic process, they patterned phosphorus atoms into functional devices on the crystal then covered them with a non-reactive layer of hydrogen.

Hydrogen atoms were removed selectively in precisely defined regions with the super-fine metal tip of the STM. A controlled chemical reaction then incorporated phosphorus atoms into the silicon surface.

Finally, the structure was encapsulated with a silicon layer and the device contacted electrically using an intricate system of alignment markers on the silicon chip to align metallic connects. The electronic properties of the device were in excellent agreement with theoretical predictions for a single phosphorus atom transistor.

Check out a video demonstration of the system here.

newsroom.unsw.edu.au