Global Sources
EE Times-Asia
Stay in touch with EE Times Asia
EE Times-Asia > Optoelectronics/Displays

Creating more cost-effective GaN LEDs for homes

Posted: 14 Oct 2014 ?? ?Print Version ?Bookmark and Share

Keywords:University of Cambridge? gallium nitride? blue LED? Plessey Semiconductors?

This year's Nobel Prize for Physics recognises the invention of blue light-emitting diode (LED) as one of the breakthrough technologies that benefit the public. Now, researchers from the University of Cambridge are pushing the limits further by trying to develop more cost-effective gallium nitride LEDs that can have widespread use in homes and offices.

Plessey Semiconductors, a British manufacturer, is vying to be the first company to make energy-efficient LEDs for home lighting at a price that consumers will pay, and they're using a technology developed by Cambridge researchers.

In 2012, Plessey acquired the technology for growing a remarkable man-made material that can emit light in every part of the colour spectrum when electricity passes through it. They recommissioned a mothballed processing plant, created new jobs and hired three researchers from the University of Cambridge. Their aim: to put energy-efficient lighting within financial reach of the consumer.

Prototypes of their LEDs rolled off the production line later that year, and by April 2013 the company was gearing up to fulfil its first commercial orders. In just 15 months, Plymouth-based Plessey had gone from never having made an LED to being the world's first manufacturer of commercially available LEDs made on large-diameter silicon substrates.

Today, the company is addressing a global market that, according to a report released in 2013 by WinterGreen Research, could be worth up to $42 billion by 2019. What gives Plessey an edge over its competitors is its ability to manufacture LEDs at a fraction of the costs, thanks to a unique process developed by Sir Colin Humphreys, professor in the Cambridge Centre for Gallium Nitride.

Blue and white gallium nitride (GaN) LEDs have been commercialised around the world since Shuji Nakamura in Japan developed a method of growing thin GaN layers on sapphire in the early 1990s. Although GaN LEDs are now expected to dominate the world market for lighting, their performance and cost both need to be improved. (Read more: Blue LEDs win Nobel Prize)

Humphreys' team developed a way of growing GaN on the vastly cheaper substrate silicon and, crucially, a means of scaling this for commercial purposes. "We've got lower costs for growing GaN LEDs on silicon than anyone else we know," noted Humphreys. "Potentially, this is an advantage that puts Britain right at the forefront of LED research."

Competition between manufacturers, including Toshiba and Samsung, to lead the market in competitively priced LEDs has been intense, driven by the increasing demand for energy-efficient lights.

LED bulbs have much longer working lives than any other forms of artificial lighting: LEDs can last for 100,000 hours compared with 10,000 hours for fluorescent tubes and 1,000 hours for tungsten filament light bulbs. LEDs in dashboards frequently outlive the life of the car; LED light bulbs in the home would probably have to be changed only once in a person's lifetime.

LEDs also use less energy than other forms of lighting. UK homes use 20 per cent of their energy on lighting and, because LEDs use 90 per cent less energy than incandescent bulbs, Humphreys said the superior energy efficiency of LEDs could reduce CO2 emissions. It's little wonder that LEDs have been hailed as a lighting revolution.

Yet, few homeowners have invested in LEDs for home lighting.

Humphreys' team has pioneered a technique for depositing successive layers of GaN and indium GaN, each only 5-10 atoms thick and growing at the speed of grass, on a 6in silicon wafer. The wafer is then cut into up to 150,000 pieces, each of which forms the heart of a small LED. Using this technology, Plessey hopes to become the commercial leader in GaN-on-silicon LEDs, producing billions per year.

"Growing GaN on silicon is quite a complex process," said Humphreys. One problem is the appearance of cracks on cooling from the growth conditions of 1,000°C. This has now been solved by the researchers through careful balancing of the tension in the material as it cools down.

Plessey acquired the technique when it bought the spin-out company CamGaN, set up by Humphreys and colleagues to commercialise the technology. The size of the silicon wafers is greater than the conventional 2in sapphire wafers, meaning a greater number of LEDs can be made. Fortuitously, Plessey had a 6in processing line that had been mothballed.

1???2?Next Page?Last Page

Article Comments - Creating more cost-effective GaN LED...
*? You can enter [0] more charecters.
*Verify code:


Visit Asia Webinars to learn about the latest in technology and get practical design tips.

Back to Top