Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Researchers at the University of Wisconsin, Madison, have made ultrathin silicon transistors that operate more than 50 times faster than previous flexible-silicon devices. The advance could help make possible flexible high-end electronics that would be useful in a variety of applications, from computers to communication. Zhenqiang (Jack) Ma, professor of electrical and computer engineering and lead researcher on the project, is interested in using flexible electronics to redesign large-scale antennas that could be molded in the shape of, say, an airplane. For instance, radar antennas could be made to cover a large area on an airplane, he says, increasing sensitivity and area of coverage.

Most flexible electronics, such as those used in e-paper and roll-up displays for mobile devices, rely on transistors made of either organic polymers, printed directly on a plastic substrate, or amorphous, or noncrystalline, silicon. However, transistors made of these materials can’t perform at the gigahertz speeds needed for complex circuitry or antennas. “People have for some time been able to make slow flexible electronics,” but the speed of the transistors has been limited, says Max Lagally, professor of materials science and physics at the University of Wisconsin and collaborator of Ma. The next step, he says, has been to make the transistors out of high-quality, single-crystal silicon instead of organic polymers and amorphous silicon because electrons simply move faster in single-crystal silicon.

Ma says his research, published in Applied Physics Letters, is an extension of the previous work done to put high-quality, single-crystal silicon on a flexible plastic substrate. While single-crystal silicon is normally stiff, it can bend if made thin enough. Previously, researchers at the University of Illinois, Urbana-Champaign, have shown that nanometer-thin films of single-crystal silicon transistors can be fabricated and successfully transferred to flexible and stretchable substrates. (See “Stretchable Silicon.”)

Work by Ma and Lagally at Wisconsin further increased the performance of the silicon by adding strain to its crystalline structure, a technique used by Intel and other chip makers to increase the electron mobility of the material. (See “High-Quality Flexible Silicon.”) But, says Ma, “high electron mobility is not equal to high device speed.” Speed of a device is also dependent on its engineering, he says, specifically the resistivity of the contact connections–the points on the transistor where electrons flow in and out of the device.

0 comments about this story. Start the discussion »

Credit: Jack Ma, University of Wisconsin, Madison

Tagged: Computing, silicon, flexible electronics, transistors, e-paper

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me