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Independent Professional: Experienced educator and management consultant for engineering educational institutions, researcher, trainer, technical consultant on sustainable technologies, related to cement manufacturing and characterisation, using industrial and agricultural wastes in cement and concrete, durability of concrete and fuel cell power.

Thursday, February 19, 2009

Low-cost LED:

Dr J D Bapat

We are very close to achieving highly efficient, low cost white LEDs that can take the place of both traditional and currently available low energy light bulbs. That won’t just be good news for the environment. It will also benefit consumers by cutting their electricity bills. In addition to the environmental and cost benefits of LEDs, the technology is expected to enable a wide range of advances in areas as diverse as healthcare, transportation systems, digital displays and computer networking.

A light-emitting diode (LED) is a semiconductor diode that emits light when charged with electricity. The LEDs are used for display and lighting in a whole range of electrical and electronic products.

A new way of making LEDs could see household lighting bills reduced by up to 75% within five years. Gallium Nitride (GaN), a man-made semiconductor used to make LEDs (light emitting diodes), emits brilliant light but uses very little electricity. Although GaN was first produced over 30 years ago, it is only in the last ten years that GaN lighting has started to enter real-world applications. Currently, the brilliant light produced by GaN LEDs is blue or green in colour. A phosphor coating is applied to the LED to transform this into a more practical white light. Until now high production costs have made GaN lighting too expensive for wide spread use in homes and offices.

With funding from the Engineering and Physical Sciences Research Council (EPSRC), the Cambridge University based Centre for Gallium Nitride has developed a new way of making GaN which could produce LEDs for a tenth of current prices.
The Cambridge Centre for Gallium Nitride was established in 2000.


The Engineering and Physical Sciences Research Council (EPSRC) is the UK’s main agency for funding research in engineering and the physical sciences. The EPSRC invests around £740 million a year in research and postgraduate training, to help the nation handle the next generation of technological change. The areas covered range from information technology to structural engineering, and mathematics to materials science. This research forms the basis for future economic development in the UK and improvements for everyone’s health, lifestyle and culture. EPSRC also actively promotes public awareness of science and engineering. EPSRC works alongside other Research Councils with responsibility for other areas of research. The Research Councils work collectively on issues of common concern via Research Councils UK.

GaN LEDs are currently grown on 2-inch sapphire. In comparison to that, it is possible to produce 10 times as many LEDs on a 6-inch silicon wafer. The processing costs remain essentially the same. The 6-inch silicon wafer is much cheaper to produce than a 2-inch sapphire wafer. Together these factors result in a cost reduction of about a factor of 10. This lower cost method could mean cheap mass produced LEDs become widely available for lighting homes and offices in the next five years.

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