Physicists of the University of New South Wales and Purdue University, created a new transistor from a single phosphorus atom. The new transistor is the smallest transistor ever built. The new created transistor can help in building function quantum computers to replace the silicon machines that we use today.
In the picture: This is a single-atom transistor: 3D perspective scanning tunnelling microscope image of a hydrogenated silicon surface. Phosphorus will incorporate in the red shaded regions selectively desorbed with a STM tip to form electrical leads for a single phosphorus atom patterned precisely in the center.
The tiny electronic device, described today in a paper published in the journal Nature Nanotechnology, uses as its active component an individual phosphorus atom patterned between atomic-scale electrodes and electrostatic control gates.
Until now, single-atom transistors have been realised only by chance, where researchers either have had to search through many devices or tune multi-atom devices to isolate one that works.
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.
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.
It is predicted that transistors will reach the single-atom level by about 2020 to keep pace with Moore’s Law, which describes an ongoing trend in computer hardware that sees the number of chip components double every 18 months.