The Hindu : Tamil Nadu / Chennai News : Cheap and clean power from LED

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Monday, Jan 12, 2009
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Tamil Nadu

Tamil Nadu - Chennai

Cheap and clean power from LED

Ramya Kannan

Energy saving is expected to be 50%

“We are attempting to replace mercury in tube lights with Ultraviolet LEDs”
It can also be used for water purification

CHENNAI: At a time when indigenous production is being promoted to reduce cost and increase accessibility, Anna University’s home-made light emitting diode (LED) offers promise.

Researchers at the Crystal Growth Centre, the university’s premier institute, have developed the LED semiconductor in their laboratory at Guindy. The development has far-reaching implications for cheap and clean power throughout the country, besides helping in water purification. Energy saving from this LED is expected to be about 50 per cent, scientists claim. It will be a boon for rural electrification. While commercial products available in the market use imported LEDs, mass production of a home-made LED is likely to have tremendous cost benefits. Using a Metal Organic Chemical Vapour Deposition unit, K. Baskar and J. Kumar led their team of scientists to produce a two-inch semiconductor wafer, which would produce white light illumination. Demonstrating the equipment in the presence of Vice-Chancellor Mannar Jawahar, Prof. Kumar said the experiment, started in 2002, had borne fruit. “We are now developing Ultraviolet LEDs on the wavelength from 360 nm to 254 nm to replace conventional tube light (fluorescent lamps),” says Prof. Bhaskar. This is likely to be completed by the end of 2009, faster than what it took them to develop the process of fashioning the semi-conductor wafer. The Ultraviolet LED will have an edge over the available technology and can replace the expensive LEDs currently available in the market, once the production starts.

Says Prof. Bhaskar, “We are attempting to replace the mercury in the tube lights with UV-LEDs and use the existing phosphors in conventional tube lights.” The semiconductor material for the LED structure is Aluminium Gallium Nitride. These LEDs will work for several years, longer than the conventional tube lights. Again, there are no toxic metals in the LEDs, compared with the regular tube lights that contain mercury. Waste disposal will also become easy. The double-edged advantage of the UV-LED is that it can be used for water purification as the UV source is known to kill active microbes in water.

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