Transistors Now Come in Atom Size

A computer model showing an atom sitting in a channel in a silicon crystal. Credit: Purdue University via Science Daily

Through a trans-pacific effort over collaboration technology “nanoHUB”, researchers have managed to build the tiniest transistor that ever was, and ever could be.

They used a single phosphorous atom to act as a conductor inside the tiny chip, creating a single-atom transistor that’s unique from its predecessors in that this is the first time we’ve been able to achieve placement of the single atom with controllable atomic precision.

So what’s the catch? The chip needs to be kept at temperatures similar to liquid nitrogen – negative 196 degrees Celcius/negative 391 degrees Fahrenheit. This is because the technique involves keeping electrons in a “well” or “channel”. At higher temperatures, the electrons escape the channel, meaning the atom no longer acts like a metal. Once someone determines a way to contain the electrons without the low temperatures, we’ll be sweet to truly stuff a chip with transistors that are 0.1 nanometres across!

This is quite literally the physical limit: we can’t physically go smaller than this (by the physics we know…but let’s not think about that just for now). This means it’s the end of “Moore’s Law” which basically works off the historical trend of processing speed developments that suggests that the number of transistors that can be installed on a chip doubles in a period of about 18 months. With these atomic-sized transistors, this doubling is no longer possible, within the limits of physics.

But that doesn’t mean that technology won’t get any better than this. The real progress that comes from this development is not the improvement on old technology, but indeed forging new technology: quantum computing.

The concept of controlling the electrons in the atom (to make it work like a metal) is what can be used to achieve quantum computing: electrons can be encoded with the quantum information (the “qubits”) and therefore if we can control the electrons, we can control the quantum information.

Of course, we are yet at a point where we can actually control those electrons, which casts doubt on whether we will actually ever be able to do it or not, but this is a definite step in the right direction. While this single-atom transistor is more clearly going to allow silicon chips to progress further than they ever have before, achieving quantum coherence when controlling a large number of qubits has yet to be proven.

That hardly diminishes the significance of this incredible milestone: reaching physical limits is always an exciting point to reach, and now that we’re here, we can start doing things that may have always been thought impossible.

The achievement was performed at the University of New South Wales in Australia under direction of Professor Michelle Simmons and in cooperation with groups under Professor Gerhard Kilmeck at Purdue University in the US and Professor Hollenberg at the University of Melbourne in Australia.

The use of nanoHUB played an important part in establishing an international collaborative community that benefitted the scientists both in their scientific progress as well as their own personal relationships. Major win for science-geek social networking.

[Via Science Daily]

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