'Nanospikes' Add To Solar, Biomedical, Microelectronics Applications (10/24/2007)

Laser textured germanium surface with nanospikes. (Credit: Image courtesy of Prof. Mool C. Gupta, University of Virginia)

New technology in development at the University of Virginia School of Engineering and Applied Science could lead to more successful hip and bone replacement surgeries, make better use of solar power and even prevent your computer from overheating.

Through the creation of nano/micro laser texturing and "nanospikes" on the surfaces of semiconductors and metals, Mool C. Gupta, Langley Distinguished Professor in U.Va.'s Charles L. Brown Department of Electrical and Computer Engineering, is adding a new dimension to these materials' effectiveness.

Gupta, who is also the director of the National Science Foundation's Laser Industry/University Cooperative Research Center, has long studied the nano- and micro-textures on a variety of materials, such as silicon (Si), germanium (Ge) and metals. This texture, he explains, is like sand on sandpaper - the added hills and valleys make for greatly increased surface area, which, in the case of a Ge or Si photodetector, means greater absorption and reduced reflection of light - but in a more controlled manner.

What Gupta has done in creating nanospikes on Ge's surface is add another, more minute, layer of texture, vastly increasing the surface area and thus effectiveness of the material. Despite their incredibly small size - nanospikes' tips range from 10-100 millionths of a meter in diameter - these tiny, performance-enhancing nanostructures could have a big impact on many aspects of our everyday lives.

Gupta predicts that nanotextured Si, Ge and other semiconductors will greatly increase effectiveness in optoelectronic technologies such as optical communications as well as solar energy. In addition, together with Barada Nayak (EE '07), who recently earned his Ph.D. in electrical engineering from U.Va., Gupta is exploring several other avenues for his nano- and micro-texturing and nanospike research.

"We are now able to successfully texture metals like stainless steel and titanium, one of the more commonly used implant metals for hips or joints," Gupta says. "As the world's elderly population grows and as people are living longer, implants like these are much more common. We are working with Dr. Cato Laurencin in U.Va.\'s Orthopaedic Surgery Department to see how the cells grow on these laser-textured surfaces - the idea is that if you can have enhanced cell growth and improved osseo-integration, those implants are more likely to be accepted by the body for a long time."

This technology could also be used to help dissipate heat efficiently in computer chips, making computers less likely to overheat when running multiple tasks, and enhance adherence of material surfaces to one another, Gupta adds.

With many anticipated applications for this novel nanotechnology, Gupta and Nayak have worked with the U.Va. Patent Foundation to file an international patent application. They plan to create a spin-off company to explore various commercial applications of nano- and micro-texturing and nanospikes.

"Mool Gupta and Barada Nayak have developed a very interesting technology that has a lot of potential," says Chris Harris, senior licensing manager for the U.Va. Patent Foundation. "In addition to the primary application in the area of photovoltaics - using the laser nano- and micro-texturing process to affect light trapping and make solar cells more efficient - there are a number of other very innovative applications, such as thermal management in integrated circuits, bioengineering tissue scaffolds, beam blocks and etching numbers onto a super-small part."

Note: This story has been adapted from a news release issued by the University of Virginia

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