A team of engineers at the University of Utah, led by electrical and computer engineering professor Massood Tabib-Azar, has discovered a way to produce microscopic electronic switches that are truly open when turned off — thus eliminating bias current and potentially saving large amounts of energy. The design could cut “vampire currents” in appliances and perhaps allow smartphones and laptops to run longer on a battery charge.
Unlike a mechanical switch, transistors waste small doses of electricity while they are in a waiting or off state. The new kind of switch uses solid electrolytes, such as copper sulfide, to literally grow a wire between two electrodes when an electrical current passes through them, turning the switch on. When you reverse the polarity of the current, the metallic wire between the electrodes breaks down, leaving a gap between them, and the switch is turned off. A third electrode is used to control this process of growing and breaking down the wire.
“The distance between the two electrodes where the wire is grown can be as little as a nanometer long,” Tabib-Azar said. Thus, billions of these switches could be built onto a processor or memory. He added that this process doesn’t require expensive retooling of manufacturing plants to implement it because these plants already use similar materials.
University of Utah electrical and computer engineering professor Massood Tabib-Azar. Photo Credit: Dan Hixson/University of Utah
Professor Tabib-Azar said that “the switch process is about 100 times slower than a transistor.” He noted that the wear mechanism is well understood and should result in very long endurance — much like that of a transistor. The research was published in a paper in the current issue of Solid-State Electronics. The paper was co-authored by Pradeep Pai from Intel, Yuying Zhang from Omnivision Technologies, and Nurunnahar Islam Mou from IM Flash. More information is available at http://unews.utah.edu/category/research.
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