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Research team touts room-tem silicon spintronics

Posted: 01 Dec 2009 ?? ?Print Version ?Bookmark and Share

Keywords:spintronics? transistor? silicon electron?

University of Twente researchers claim they can control a silicon electron's spin at room temperature.

Digital electronics is almost universally based on the detection and control of the movement of electrons through the electrical charge associated with them. However electrons also have the property of spin and transistors that function by controlling an electron's spin orientation, instead of its charge, would use less energy, generate less heat and operate at higher speeds. That theory has resulted in a field of research called spintronics. However, until now this has required low temperatures for operation.

Indeed, as the University of Twente authors comment, the ability to detect spin polarization in otherwise non-magnetic semiconductorsincluding gallium arsenide and siliconusing all-electrical structures has only been achieved at temperatures below 150K (-123C) and in n-type materials, which has limited further development.

The authors state that they have demonstrated room-temperature electrical injection of spin polarization into n-type and p-type silicon from a ferromagnetic tunnel contact, spin manipulation using the Hanle effect and the electrical detection of the induced spin accumulation.

The spin splitting has a life time of greater than 140ps for conduction electrons in heavily doped n-type silicon at 300K (26.85C) and greater than 270ps for holes in heavily doped p-type silicon at the same temperature.

Nonetheless, the results open up the possibility of embedding spintronic operation in complementary silicon operating at ambient temperature.

In order to achieve the breakthrough, the team, led by Ron Jansen at the Mesa Institute for Nanotechnology at the University of Twente, inserted a layer of aluminum oxide between the magnetic material and the semiconductor that is less than one nanometer thick.

The thickness and quality of this layer are crucial. The information is transferred by applying an electric current across the oxide interface, thereby introducing a magnetization in the semiconductor, with a controllable magnitude and orientation. The researchers found that the spin information can propagate into the silicon to a depth of several hundred nanometers. This is sufficient for the operation of nanoscale spintronic components.

The next step is to build electronic components and circuits and use them to manipulate spin information, the research team said.

- Peter Clarke
EE Times Europe

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