Scientists push electronics down to picometer electronics

Forget the era of nanotechnology; researchers at top universities and electronics firms are racing to push electronics into the pico-age.

I. One-Atom Transistor Sets New Bar for Construction Techniques

Two impressive discoveries were reported over the last week that illustrate that while optical die-shrinks may be getting long in the tooth, circuit technology may have a ways to go before reaching intrinsic atom-scale barriers.

The first discovery was announced by the University of New South WalesCentre for Quantum Computer Technology (CQCT) and Purdue University, who claim to have made substantial progress in the commercialization of 1-atom transistors.  While not the first 1-atom transistor observed, the group claims it is the first to create the tiny picometer transistor purposefully and reliably, allowing verifiable results, versus past accidental discoveries.

The team's production technique involves coating a silicon wafer with hydrogen, then selectively removing various hydrogen atoms using the super-fine metal tip of a scanning tunneling microscope.  While this part of the study essentially seemingly acts in a top-down fashion, similar to traditional photolithography methods, the next step takes circuit construction in a different direction.  

The selected lingering hydrogens are then exposed to phosphine (PH3).  The phosphine's loan electron pair binds to the hydrogen, attaching it in a selective fashion to the board.  The hydrogen atoms are then washed away in a process similar to acid etching.  The researchers refer to this approach of affixing atoms to select points, rather than etching away atoms selectively as a "bottom-up" circuit building approach.

1-atom transistor
The single-atom phosphorous transistor (center) will be a building block for quantum computers. [Image Source: University of New South Wales]

The transistor's size is about 128 picometers, according to the radius of a phosphorous atom [source].

Silicon guides then attached nanowires to the device, allowing the single-atom transistor's switching properties to be measured.  The entire device was finally encased in a protective layer of silicon.  The measured properties corresponded with theoretical predictions, according to the study.

One atom transistor
The tiny element was mounted to measurement probes.
[Image Source: University of New South Wales]

Versus a 10 nm positional error in previous designs, the new design offers much finer positional deposition control.  Before, the team had produced 7 atom designs had been produced reliably as of 2010, gradually working down the scale of their technique.

States lead author Dr. Martin Fuechsle, a UNSW post-grad, "The thing that's unique about the work that we've done is that we've with atomic precision positioned this individual atom within our device."

The new work was published in the prestigious peer-reviewed journal Nature Nanotechnology.

The research team hopes to combine the device with the 1-atom high wire [1][2] they revealed in January, in order to create prototype quantum computers, which perform calculations on qubits, special subatomic-level information stores which employ the quantum physical principles of entanglement and superposition.

II. World's Tiniest Magnetic Storage Device is Created

In similar news, International Business Machines, Inc. (IBM), fresh off its 100-year anniversary celebration, has created the world's smallest magnetic-storage device, a 12 atom construct.

Today, magnetic storage dominates much of the world's permanent storage, with hard drives being the cheapest solution for reliable high-volume storage.  But the constant advance of memory densities, which today has granted us terabyte drives is at an uncertain cross-roads, as researchers attempt to figure out how to create tinier nanoscopic structures, without losing the core constant stored magnetic state.

Andreas Heinrich creator of the new storage array learned from trial and error.  An earlier 8-atom construct, seemed promised, but turned out to spontaneously switch between quantum states, making measurement -- or storage -- impossible.  Professor Heinrich comments, "[The 8 atom] system will just spontaneously hop from one of those states to another state in a timescale that is too fast for us to claim anything like a data storage [demonstration]. It might be switching 1,000 times per second."

12 atom storage
A byte -- 8 bit chunks, with 12 atoms each, shown w. stray xenon atoms. [Image Source: IBM]

Creating an operational device required unusual measures.

The first is that unlike traditional magnetic storage that relies of ferromagnetism -- largely blocks of consistently aligned atoms -- the new device stores data in an anti-ferromagnetic fashion.  By having the atoms face in different directions, interference between adjacent bits is limited.  IBM, inventors of the scanning tunneling microscope (STM) 30 years ago, used their creation to construct the tiny, fragile device.

The new memory stores data in an anti-ferromagnetic format. [Image Source: IBM]

Second, in order to maintain magnetism in a 12-atom construct, researchers needed to keep the atoms at a chilly 1 Kelvin (-458 Fahrenheit), colder than outer space.  If the temperature crept up to room temperature, Professor Heinrich estimates that the device would require 150 atoms.

That may sound less desirable, but consider that current drives by storage leaders like Hitachi, Ltd. (TYO:6501) require an estimated 800,000 to 1,000,000 atoms to store data.  So the scaled up version of the miniature laboratory device, could off over 1,000 times more storage room temperature, assuming manufacturing techniques can be developed to produce it.

The possibility of petabyte (1,000 terabyte) drives may seem extravagant and unnecessary, but mankind will surely eventually require them -- recall megabyte sized drives were once viewed as of questionable necessity.

IBM is researching many novel storage technologies, both within and outside the magnetic storage realm.

Sources: University of New South Wales, Nature Nanotechnology, IBM

"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov

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