An inexpensive approach to make flexible and high speed silicon-based transistors, which may soon be used in the next generation of hi-tech wearables, has been devised by a team of researchers from the University of Wisconsin-Madison.

A technique named nanoimprint lithography has been applied to create these flexible transistors.

In this process, a sheet of light sensitive material is blasted, using beams of electrons that create very narrow measuring shapes (about 10-nanometers-wide), to form a reusable mold with which a flexible silicon membrane is created.

A nanoscale knife is then used to precisely cut trenches of nanometer scale in the silicon membrane similar to the patterns in the mold, and then wide gates are added on top of the trenches to serve as switches.

This results in a small flexible transistor that can bend easily and has the ability to wirelessly transmit data with a potential to operate at 38 GHz, though it is believed that it can be pushed to a speed of 110 GHz, putting it in the same category as the fastest computers.

These transistor channels have the ability to send data or power, which when combined with flexibility and thinness, could lead to wearables that are much more powerful than what is available today.

The 3D pattern makes the transistor operate efficiently by consuming less power and energy. The molds are also reusable, making the technique quite inexpensive considering its speed and efficiency.

The technology has been formulated by Zhenqiang (Jack) Ma, the Lynn H. Matthias Professor in Engineering and Vilas Distinguished Achievement Professor in electrical and computer engineering, research scientist Jung-Hun Seo, and their team.

According to Ma, the small size makes it possible to put more than one transistor on a device, which increases its speed and functionality. Also, since the mold is reusable, this technique can be used for roll-to-roll processing that allows manufacturers of semiconductors to mass produce several devices on a single roll of flexible plastic, repetitively.

"Nanoimprint lithography addresses future applications for flexible electronics," said Ma. "We don't want to make them the way the semiconductor industry does now. Our step, which is most critical for roll-to-roll printing, is ready."

The technology though is still at a nascent stage and wouldn't be used commercially as yet!

The study is published in the journal Scientific Reports.

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