Researchers look beyond silicon for next-gen transistors

An MIT researcher has warned that the recent rapid pace of microelectrical technological development will soon come to a "screeching halt" unless radical new transistors are developed.

Jesus del Alamo, an MIT professor of electrical engineering and computer science and member of MIT's Microsystems Technology Laboratories (MTL), warned: "Unless we do something very radical pretty soon, the microelectronics revolution that has enriched our lives in so many different ways might come to a screeching halt."

He added that engineers estimate that within the next 10 to 15 years we will reach the limit, in terms of size and performance, of silicon transistors.

"Each of us has several billion transistors working on our behalf every day in our phone, laptop, iPod, car, kitchen and more," del Alamo added.

He explained that, as a result, his lab and others around the world are working on new materials and technologies that may be able to reach beyond the limits of traditional silicon.

"We are looking at new semiconductor materials for transistors that will continue to improve in performance, while devices get smaller and smaller," he said.

One such material del Alamo and his students at the MTL are investigating is a family of semiconductors known as III-V compound semiconductors. Unlike silicon, these are composite materials.

According to del Alamo, a particularly hot prospect is indium gallium arsenide, or InGaAs, a material in which electrons travel many times faster than in silicon. As a result, it should be possible to make very small transistors that can switch and process information very quickly.

Del Alamo's group recently demonstrated this by fabricating InGaAs transistors that can carry 2.5 times more current than state-of-the-art silicon devices. More current is the key to faster operation. In addition, each InGaAs transistor is only 60 nanometers, or billionths of a meter, long. That's similar to the most advanced 65-nanometer silicon technology available in the world today.

"The 60-nanometer InGaAs quantum-well transistor demonstrated by Professor del Alamo's group shows some exciting results at low supply voltage (eg 0.5V) and is a very important research milestone," said Robert Chau, senior fellow and director of transistor research and nanotechnology at Intel, a sponsor of the work.

Del Alamo notes, however, that InGaAs transistor technology is still in its infancy. Some of the challenges include manufacturing transistors in large quantities, because InGaAs is more prone to breakage than silicon.

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