A team of scientists at the Tyndall National Institute have designed and fabricated the world’s first junctionless transistor that could revolutionise microchip manufacturing in the semiconductor industry.

Prof Jean-Pierre Colinge’s breakthrough on the microchip transistor was published today in Nature Nanotechnology, one of the most prestigious scientific research publications.

The news breathes fresh hope for the local economy and puts extra weight behind the nation’s aspirations to be a world-leading nanotechnology hub, effectively the future for computing and areas like healthcare, including battling cancer.

The potential of nanotechnology

Nanotechnology, the science of ultra-micro electronics and pharmaceuticals, has the potential to be a major engine of growth in the Irish economy and exports could be doubled from €15 billion today to €30 billion by 2015.

The achievement will add extra impetus to calls to create a Nanotech Competency Centre to bolster Ireland’s future industrial ambitions.

The transistor is the fundamental building block in all electronic devices. Since the early Seventies, the number of transistors in a silicon chip has grown from a few hundred to more than 2 billion transistors on a single chip today.

The exponential increase in demand for feature-packed electronic devices is driving the semiconductor industry to produce chips that need to be smaller, more energy efficient and more cost effective than ever before.

As a consequence, transistors are becoming so small that conventional transistor architectures, used since the Seventies, can no longer be used.

“We have designed and fabricated the world’s first junctionless transistor that significantly reduces power consumption and greatly simplifies the fabrication process of silicon chips,” said Colinge.

Fabrication of current technologies

Current technologies require fabrication processes that are both complex and costly. All existing transistors are based on junctions. A junction is formed when two pieces of silicon with different polarities are placed side by side.

Controlling the junction allows the current in the device to be turned on and off and it is the precise fabrication of this junction that determines the characteristics and quality of the transistor and is a major factor in the cost of production. Tyndall National Institute’s ground-breaking junctionless transistor doesn’t require a junction.

The current flows in a thin silicon wire and the flow of current is perfectly controlled by a “wedding ring” structure that electrically squeezes the silicon wire in the same way you might stop the flow of water in a hose by squeezing it.

These structures are easy to fabricate even on a miniature scale, which leads to the major breakthrough in potential cost reduction,” explained Colinge.

Another key challenge for the semiconductor industry is reducing the power consumption of microchips.

“Minimising current leakage is one of the main challenges in today’s complex transistors. The Tyndall junctionless devices have near-ideal electrical properties and behave like the most perfect transistors. Moreover, they have the potential of operating faster and using less energy than the conventional transistors used in today’s microprocessors,” said Colinge.

He went on to say that the junctionless transistor resembles in a way the first ideal transistor structure, proposed in 1925. But to date, no one had been able to fabricate it. He attributed the successful fabrication at Tyndall to the skill and expertise of researchers who were able to fabricate silicon nanowire with a diameter of a few dozen atoms using electron-beam writing techniques and expertise available at Tyndall.

“We are very excited by the outstanding results that Jean-Pierre has achieved,” commented Tyndall CEO, Prof Roger Whatmore. "We are beginning to talk about these results with some of the world’s leading semiconductor companies and are receiving a lot of interest in further development and possible licensing of the technology.

“These results could not have been achieved without the expertise of Jean-Pierre and his colleagues together with the state-of-the art facilities that we have at Tyndall. Funding for the work came from the substantial investment by DETE, SFI and HEA in Tyndall and these results demonstrate the value of that investment in research and development.

“In a very short time, Ireland is gaining recognition as a world leader in many technological areas and this investment needs to ensure Ireland’s economic recovery,” Whatmore said.

By John Kennedy

Photo: A breakthrough on the microchip transistor by Prof Jean-Pierre Colinge and his team at Tyndall National Institute has been published in Nature Nanotechnology