MIT applies invisibility to electronics
The concept—described in a paper in the September edition of the journal Physical Review Letters—appears to work in computer simulations, according to the researchers. The researchers are moving on to building actual devices to see whether they perform as expected.
According to Gang Chen, a mechanical engineering professor at MIT and one of the authors of the paper, the new concept could improve the flow of electrons by orders of magnitude and eventually lead to more efficient filters and sensors. As the components on semiconductors get smaller, the new concept could be used as a better strategy for electron transport, Chen said.
Credit: Bolin Liao et al, MIT
The concept could also lead to a new kind of switches for electronic devices, according to Chen. The switch could operate by toggling between transparent and opaque to electrons, thus turning a flow of them on and off, he said. "We’re really just at the beginning," Chen said. "We’re not sure how far this is going to go yet, but there is some potential" for significant applications.
The initial concept was developed using particles embedded in a normal semiconductor substrate. But the MIT researchers would like to see if the results can be replicated with other materials, such as two-dimensional sheets of graphene, which might offer interesting additional properties.
Previous work on cloaking objects from view has relied on so-called metamaterials made of artificial materials with unusual properties. The composite structures used for cloaking cause light beams to bend around an object and then meet on the other side, resuming their original path—making the object appear invisible.
"We were inspired by this idea," Chen said. In the new electron-cloaking material developed by Chen and his colleagues, the process is slightly different, he said.
Normally, electrons travel through a material in a way that is similar to the motion of electromagnetic waves, according to the researchers. Chen and his colleagues developed the idea of harnessing the cloaking mechanisms developed to shield objects from view—applying it to the movement of electrons.
"This was a first step, a theoretical proposal," Bolin Liao, an MIT graduate student and co-author of the paper. "We want to carry on further research on how to make some real devices out of this strategy."
In addition to Chen and Liao, members of the MIT team that developed the technology include former postdoc Mona Zebarjadi—now an assistant professor at Rutgers University—and research scientist Keivan Esfarjani.
"This is very exciting work that expands the concept of cloaking to the domain of electrons, said Xiang Zhang, a professor of mechanical engineering at the University of California at Berkeley, who was not involved in the project.The authors, Zhang said, "uncovered a very interesting approach that may be very useful to thermoelectric applications."
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