Scientists come up with superfast semiconductor

Researchers at Oregon State University say they have solved a puzzle in fundamental material science that has eluded scientists since the 1960s, by creating a high-performance “metal-insulator-metal” diode which will speed up transistors and help power tomorrow’s faster technology.

According to the university, conventional electronics made with semiconductors use transistors that help control the flow of electrons. Although they are fast and comparatively inexpensive, this approach is limited by the speed with which electrons can move through these materials. With the invention of faster computers and more sophisticated products such as liquid crystal displays, current technologies are nearing the limit of what they can do.

They have developed a metal-insulator-metal, or MIM diode that can be used to perform some of the same functions, but in a fundamentally different way. In this system, the device is like a sandwich, with the insulator in the middle and two layers of metal above and below it.

In order to function, the electron doesn’t so much move through the materials as it “tunnels” through the insulator – almost instantaneously appearing on the other side and making the switching time quicker. This means that this new technology can speed up conventional chips.

“Researchers have been trying to do this for decades, until now without success,” said Douglas Keszler, a distinguished professor of chemistry at OSU and one of the nation’s leading material science researchers. “Diodes made previously with other approaches always had poor yield and performance.”

“This is a fundamental change in the way you could produce electronic products, at high speed on a huge scale at very low cost, even less than with conventional methods.

“It’s a basic way to eliminate the current speed limitations of electrons that have to move through materials.

“When they first started to develop more sophisticated materials for the display industry, they knew this type of MIM diode was what they needed, but they couldn’t make it work,” Keszler said. “Now we can, and it could probably be used with a range of metals that are inexpensive and easily available, like copper, nickel or aluminum. It’s also much simpler, less costly and easier to fabricate.”

The findings were made by researchers in the OSU Department of Chemistry; School of Electrical Engineering and Computer Science; and School of Mechanical, Industrial and Manufacturing Engineering. The OSU diodes were made at relatively low temperatures with techniques that would lend themselves to manufacture of devices on a variety of substrates over large areas.

They said high speed computers and electronics that don’t depend on transistors are possibilities. Also on the horizon are “energy harvesting” technologies such as the nighttime capture of re-radiated solar energy, a way to produce energy from the Earth as it cools during the night.

“For a long time, everyone has wanted something that takes us beyond silicon,” Keszler said. “This could be a way to simply print electronics on a huge size scale even less expensively than we can now. And when the products begin to emerge the increase in speed of operation could be enormous.”