Toshiba's spintronics transistor and a new storage mechanism in silicon come to life
December 8, 2009
In a recent issue of the journal Nature, researchers from the University of Twente, Netherlands, explain how they succeeded in transferring magnetically coded information directly into a semiconductor, for the first time at room temperatures. Meanwhile, Toshiba announced at the International Electronics Devices Meeting (IEDM) it has developed a MOSFET transistor harnessing spintronics, demonstrating stable, fast and low-power performance.
Manipulating electronic spins in room-temperature silicon
Compared to bulky relays or vacuum tubes, today's electronics is undoubtedly a tremendous leap forward; however, despite constant advancements, representing a bit with a charge requires an high amount of power, part of which is wasted as heat, reducing efficiency and battery life in portable devices. This is where spintronics comes into play, as manipulating the spin of electrons rather than charge could save us a lot in our energy bill and give us far greater autonomy to laptops, iPods and the likes.
Considered by many as a very strong candidate for the next generation of personal electronics, research in spintronics is so active that, these days, an edition of journals like Science or Nature hardly hit the stands without mention of new advancements. Part of the reason for this is also that not much at all is known at this point, making researching spintronics a bit like walking in uncharted territory — a treasure could be hiding around nearly any corner.
We've previously covered how researchers achieved all-electric spin control. Diamonds, or rather nitrogen impurities in them, have already been shown to be an outstanding mean to both probe and quickly manipulate electronic spins even at room temperatures, but they would likely result in expensive chips that will probably never make it to mass production.
The industry's aim is therefore to use the already familiar silicon for these purposes, which is exactly what the researchers at the University of Twente managed to do. While others had already reported being able to store spin information in silicon, the Twente team is the first to achieve this at room temperatures, a necessary step for future mass production and something that will likely facilitate future research as well.
To achieve an efficient information exchange, the researchers inserted a very thin layer of aluminum oxide between the magnetic material and the semiconductor. When applying a current across this layer, which is less than one nanometer thick, the information is readily transferred to the silicon.
The researchers found that the spin information can propagate into the silicon to a depth of several hundred nanometers, which is enough to allow the operation of nanoscale spintronic components. The next challenge will be to build new circuits and components that use this acquired information to manipulate spin information rather than charge — and a very significant step in this direction has just been made public by Toshiba.
Toshiba develops its own spintronics transistor
The demonstration that Toshiba researchers gave yesterday at the International Electronics Devices Meeting in Baltimore, Maryland is a very good example of the active interest the electronics industry has with respect to spintronics. The Japanese IT giant has announced it has manufactured a MOSFET transistor — the kind which is by far the most common — using the principles of spintronics, and with lab tests verified it has a stable performance.
"Continuing advances in MOSFET devices based on current miniaturization technologies will inevitably hit a wall as they meet such problems as relative degraded performance due to the increase in the resistance of global wiring and increased power consumption due to current leakage," Toshiba says. "Spintronics is regarded as a major candidate among potential solutions to this problem, but its application in a transistor has only recently started and has only been partially proved."
Toshiba has introduced magnetic layers into the source and drain of a MOSFET cell, and successfully applied these to controlling spin direction. According to Toshiba, this device shows fast random write and access speeds with low power consumption and opens the way to next-generation non-volatile devices that can be used as reconfigurable logic devices.
While we are waiting for further details to emerge, Toshiba assured it will continue to promote development toward establishing fundamental technologies for the application of spintronics after 2015.