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LED Process Adapts Ultraviolet Light to Kill Pathogens

E coli bacteria magnified (ARS/Wikimedia Commons)

E coli bacteria magnified (USDA Agricultural Research Service/Wikimedia Commons)

Researchers from North Carolina and Japan have devised a light-emitting diode (LED) process that uses ultraviolet (UV) light to kill pathogens such as bacteria and viruses. Their discoveries are described in the May issue of the journal Applied Physics Letters (paid subscription required).

The research team included materials scientists and engineers from North Carolina State University in Durham, HexaTech Inc. in nearby Morrisville, Tokyo University of Agriculture and Technology, and Tokuyama Corporation in Japan. The team created for demonstration crystalline wafers built on aluminum nitride that the researchers believe can be fabricated into devices that kill pathogens for applications such as treating drinking water or sterilizing surgical tools.

LEDs based on aluminum nitride as a semiconductor base material can handle a lot of power and create light in a wide spectrum, particularly in the UV range. However, aluminum nitride LEDs that create UV light have been severely limited because the substrates that serve as the foundation for these semiconductors also absorbed wavelengths of UV light that are needed for sterilization and water treatment applications.

To solve this problem, the North Carolina/Japan team used computer simulation to uncover the carbon atoms in the crystalline structure of aluminum nitride responsible for absorbing most of the UV light. Eliminating the carbon in the substrate made it possible to significantly improve the amount of UV light that can pass through the substrate at the desired wavelengths.

HexaTech Inc., a spin-off company from NC State, is commercializing the research. Zlatko Sitar, a professor of materials science and engineering at NC State and co-author of the paper, is also a co-founder of HexaTech Inc. The company plans to develop this year samples of its UV optoelectronic devices that detect and control light.

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