Nano-transistor has colossal capability

U. PITTSBURGH (US) — A super-small, super-sensitive transistor could be used as an artificial atom to develop electronic materials with properties not found in nature.

The single-electron transistor, detailed in the journal Nature Nanotechnology, provides a building block for new, more powerful computer memories, advanced electronic materials, and the basic components of quantum computers

The transistor’s central component—an island only 1.5 nanometers in diameter—operates with the addition of only one or two electrons.

That capability would make it important to a range of computational applications, from ultradense memories to quantum processors, powerful devices that promise to solve problems so complex that all of the world’s computers working together for billions of years could not crack them, says Jeremy Levy, professor of physics and astronomy at the University of Pittsburgh.

The SketchSET, or sketch-based single-electron transistor, uses a sharp conducting probe of an atomic force microscope to create such electronic devices as wires and transistors of nanometer dimensions at the interface of a crystal of strontium titanate and a 1.2 nanometer thick layer of lanthanum aluminate.

Much like the Etch-a-Sketch toy for which it is named, the electronic devices can then be erased and the interface used anew.

One virtue of a single-electron transistor is its extreme sensitivity to an electric charge, Levy says. Another property of these oxide materials is ferroelectricity, which allows the transistor to act as a solid-state memory. The ferroelectric state can, in the absence of external power, control the number of electrons on the island, which in turn can be used to represent the 1 or 0 state of a memory element.

A computer memory based on this property would be able to retain information even when the processor itself is powered down, Levy says. The ferroelectric state also is expected to be sensitive to small pressure changes at nanometer scales, making the device potentially useful as a nanoscale charge and force sensor.

Researchers from Cornell University, Stanford University, the University of Michigan, the University of California, Santa Barbara, and the University of Wisconsin-Madison, contributed to the study that was supported in part by the U.S. Defense Advanced Research Projects Agency, the U.S. Army Research Office, the National Science Foundation, and the Fine Foundation.

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