Researchers evolve specially-crafted semiconductors

Friday, 29 June 2012 11:12

News & Events - Engineering News

June 29, 2012

Some of the fastest growing sectors of the economy no longer rely quite so heavily on the traditional foundations of industry: iron, copper, brick and concrete. Certainly computers still use copper wiring and most products still incorporate some amount of steel, but many important devices these days need one component above all: semiconductors.

Generally, constructed out of silicon, semiconductors face high quality standards with often complicated production processes, but researchers at the University of California at Santa Barbara have upstaged even these complex systems. Through a process of artificial evolution, scientists think they could be on their way toward growing specially tailored semiconductor materials from whole cloth.

Growing semiconductors

The innovative biomolecular engineering research was spearheaded by Lukmaan Bawazer, then a Ph.D. candidate at UCSB though since moved on to a post-doctoral position at the University of Leeds in the U.K. NewScientist notes the group started by looking at how existing animals already incorporate materials like silicon into complex biological structures, wondering whether these processes could be applied to creating industrially useful structures.

As a basis for their research, the researchers took the genetic code from a type of sponge that incorporate silica - an important component of sand and the feedstock for most semiconductors, otherwise known as silicon dioxide - into proteins used to create their skeletons.

From this basic starting point, the group used a method of encouraging the reproduction of DNA to spur mutations. By creating millions of different variations, they could be reasonably assured that there would be some significant deviation from the common root, hopefully some of which could end up being helpful in creating useful silicon structures.

Directing evolution

These countless different strands of DNA were then spread across tiny beads of polystyrene and submerged in baths of the mineral components necessary for the creation of these silicon-based proteins, generally known as silicateins. They also ran a similar process replacing silicon with titanium.

By identifying the silicateins with the most desirable properties, researchers could attempt to mimic natural selection by using what Bawazer dubbed "molecular sex" to combine the different genetic patterns.

"This genetic population was exposed to two environmental pressures that shaped the selected minerals: The silicateins needed to make (that is, mineralize) materials directly on the surface of the beads, and then the mineral structures needed to be amenable to physical disruption to expose the encoding genes," said Bawazer. "In the realm of human technologies it would be a new method, but it's an ancient approach in nature."

Evolving production methods

At present, the idea of specifically evolving semiconductors for industrial purposes is still in its infancy. Though the basic premise has been established, further engineer research and development is needed to prove the process' ability to significantly improve on traditional methods. Researchers must also prove it can be scaled up to useful levels.

However, Bawazer notes that there are already some apparent advantages to this new approach over both existing production techniques. Specifically, the long amino acid chains involved in creating most silicateins could allow for much more complicated and nuanced chemical structures. In particular there is hope that this could lead to the creation of semiconductors specifically tailored to efficiently producing and carrying power for solar cells, among other highly specific applications.

"Here we've demonstrated the evolution of material structure," said Bawazer. "I'd like to take it a step further and evolve material performance in a functional device."

Bawazer's research has been published in the Proceedings of the National Academy of Sciences.