July 21, 2009 — If the predictions are accurate, traditional silicon-based semiconductor technology will have reached its limits by 2020. But since the demand for smaller and faster electronics shows no signs of slowing, researchers and industry are vigorously pursuing alternatives.
Jiwei Lu, research assistant professor of materials science and engineering at the University of Virginia, recently won an internal Fund for Excellence in Science and Technology Distinguished Young Investigator Grant for an ambitious research plan that, if successful, could create a paradigm shift for digital logic devices, and allow Moore's Law to carry on.
Lu works with vanadium dioxide (VO2), a promising new material that could replace or at least strongly enhance the complementary metal-oxide-semiconductor technology that is used in the integrated circuits that are commonly found in portable electronic devices, from digital cameras to laptops.
Those devices are limited because they consume a good amount of power when switching between "on" and "off" states. Lu's initial research with VO2 shows promise for eliminating this charge-based switching altogether.
Lu has been growing extremely thin films of VO2 – about 100 nanometers thick – in his lab to characterize the material's microstructure and conductivity. He found that the VO2 films have poor conductivity at room temperature, but their resistivity quickly and dramatically drops when a strong electric current is passed through them.
"The physics behind this phenomenon is not very well understood," Lu said. "We believe it's an electronic structure change or electronic transition."
When Lu saw this considerable change in resistance curve, he realized that VO2 would be a perfect candidate for a new type of switching material. "It's like any light switch you have. You can just turn on and turn off the current," Lu said. "And you can make it very small and very fast."
Lu's lab has clocked the switching time of VO2 at less than 10 nanoseconds, as fast as his lab's instrumentation can measure.
Joe C. Campbell, professor of electrical and computer engineering in the School of Engineering and Applied Science, served on the grant review committee. Campbell noted that he is particularly interested in the potential for Lu's research to produce electronic circuits that consume much less power.
"This work is still in the 'twinkle in the eye' stage, but the potential payoff is enormous," Campbell said.
The $50,000 FEST grant will be used for materials, clean room facility use, and to fund a graduate student research assistant.