Toshiba spins new MOSFET

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Toshiba has developed a MOSFET cell based on spin transport electronics, or spintronics, a semiconductor technology that makes use of the spin and magnetic moment inherent in electrons.

The chipmaker says the practical performance in transistor level of the scalable spintronics-based MOSFET device promises fast random write and access speeds with low power consumption and that it opens the way to next-generation non-volatile semiconductor devices that can be used as reconfigurable logic devices, and non-volatile LSI memory chips.

The company says continuing advances in MOSFET devices based on current technologies will inevitably hit a wall as they meet problems such as relative degraded performance due to increased wiring resistance and power consumption due to current leakage. Spintronics is seen 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.

You spin me right round
Electrons in a magnetic layer naturally are spin polarized in one of two spin states, spin up or spin down, with the majority state determining the spin state. These spin states are more or less permanent in a magnetic layer, realizing a nonvolatile characteristic that can be used to store data. Spin current can be flowed into the same spin state in a magnetic layer, and this capability changes the impedance characteristics, which determine the read signal of a spin device.

Toshiba has introduced magnetic layers into the source and drain of a MOSFET cell, and applied these to controlling spin direction by the spin-transfer-torque-switching (STS) method, and by applying gate and source/drain voltages. A magnetic tunnel junction3 is applied for write operation of STS in the magnetic layers, which are formed with full-Heusler alloy, an intermetallic that acts as a high spin polarizer.

Toshiba says the first spintronics products should appear around 2015.


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