Using technology developed by Cambridge researchers, British manufacturer Plessey Semiconductors is racing to be the first company to make affordable energy efficient LEDs for home lighting.

Our relationship with the Cambridge research group will help us push this technology to its highest potential

Dr Keith Strickland Chief Technology Officer, Plessey

This is an advantage that puts Britain right at the forefront of LED research

Professor Sir Colin Humphreys, University of Cambridge

Remarkable materials

In 2012, Plessey acquired the technology to grow a remarkable man-made material that can emit light in every part of the colour spectrum when electricity passes through it. They re-commissioned 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 light-emitting diodes (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.

Thanks to the technology from Cambridge, the company is now addressing a global market that could be worth up to $42 billion by 2019. “There are huge players in the market but we were first to market with GaN-on silicon LEDs,” said Dr Keith Strickland, Chief Technology Officer of Plessey.

 

LEDs for all

Competition to lead the market in competitively priced LEDs is intense, driven by 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 also use less energy than other forms of lighting. The superior energy efficiency of LEDs could potential save the UK £2 billion per year in energy, and reduce CO2 emissions. Yet, few homeowners have invested in LEDs for home lighting. “A 48-watt equivalent LED bulb costs around £15. Although it will save people money over its lifetime, very few people will pay this. We think we can reduce the cost to £3,” said Professor Sir Colin Humphreys of the Cambridge Centre for Gallium Nitride.

 

Sapphire to silicon

What gives Plessey an edge over its competitors is its ability to manufacture LEDs at a fraction of their costs, thanks to a unique process developed by Humphreys. Blue and white gallium nitride (GaN) LEDs have been known 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. Humphreys’ team has developed a way of growing GaN on the vastly cheaper substrate silicon and, crucially, a means of scaling this up for commercial purposes.  Plessey acquired the technology when it bought their spin-out company CamGaN. “When we launched CamGaN, we were contacted by companies all over the world wanting to utilise the technology,” said Humphreys. “The research has been funded by the UK government and it was important to us that this research be exploited here in the UK.”

 

A brighter future

Back in Cambridge, the research continues. A new £1 million growth facility funded by EPSRC has been installed at the University.  The benefits could go far beyond home lighting, to biomedicine and power electronics. In collaboration with the University of Manchester, the Cambridge team plan to build tiny LED devices that can be implanted by keyhole surgery in cancer patients to help target radiotherapy beams. Projects with the Universities of Glasgow and Strathclyde are also investigating GaN transistors as power electronics in devices that manage electrical energy and LEDs as light-based Wifi (Li-Fi).