Friday, April 17, 2015

No. 873: An LED that emits 10 times stronger deep ultraviolet (April 18, 2015)

The National Institute ofInformation and Communications Technology and Tokuyama Corp. jointly developed an LED that emits 10 times stronger deep ultraviolet than the existing LED. Ultraviolet is highly effective in sterilization. They used a gallium nitride material that was used by blue LEDs awarded by the Noble Physics Prize in 2014. The newly developed LED can kill nearly all germs within a 10 cm square area in one second. They plan to commercialize it by 2020 for sterilization as well as for the treatment of skin diseases. 

 A newly developed LED that emits
10 times stronger deep ultraviolet 

The newly developed LED allows a 0.1 square mm element to emit up to 90 mw, whereas about 10 mw is the maximum under the current technology. In addition to gallium nitride, they used aluminum nitride for the substrate. They lined up bumps, each of which is 500 nm wide, in an orderly manner on the substrate surface to allow deep ultraviolet to get out easily.

Deep ultraviolet is ultraviolet whose wavelength is between 200 and 300 nm. Although it is contained in sunlight, it hardy reaches to the ground because it is mostly absorbed in the ozone layer. 
Further details are available here (in Japanese).
You can read the details of this newly developed LED in Applied Physics Letters.    

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