Business Weekly - Cambridge, UK

Prof Colin Humphreys, an internationally recognised expert on miracle compound gallium nitride (GaN) has, along with his lab at Cambridge University, been tasked with the “very tough challenge” of enabling the low-cost manufacture GaN LEDs as part of a £3m DTI project.

A consortium of Filtronic, Forge Europa, QinetiQ, Thomas Swan Scientific Equipment, the semiconductor equipment manufacturer based in Cambridge and Humphreys’ team are working together on a three-year contract within the DTI technology programme, worth just under £3m, to develop a route to low cost LEDs for solid state lighting.

High brightness light emitting diode (LED) lamps are a low cost, long life and efficient replacement for standard light bulbs, reducing energy requirements by at least 75 per cent.

Since lighting currently accounts for 20 per cent of all electricity demand in the UK, use of LED lamps will give major energy savings without the environmental problems and short lifetimes of other bulbs.

At present a major barrier to using LEDs is the relatively high cost: this project will use large scale semiconductor processing methods for GaN based light emitting structures grown on silicon substrates to reduce costs and improve consistency.

Over the next three years, Prof Humphreys’ GaN group will be attempting to overcome the fundamental scientific challenges inherent in using traditional semiconductor manufacturing techniques to produce GaN LEDs.

This means the group will have to achieve something close to the glittering prize in GaN research by developing a “recipe” for growing the LEDs on 6 inch silicon – the semiconductor industry standard for production – instead of far more expensive materials such as silicon carbide and sapphire.

The fundamental physics involved means that current know-how can only produce low-quality, brittle LEDs on silicon.

Prof Humphreys said: “This is a tough problem to solve. If it wasn’t, one of the big companies like Osram would have already solved it.

“But we have some new ideas and I’m optimistic about our chances of success.

“I believe that in three years, we will have grown high quality GaN LEDs on six inch silicon meaning that within five years this technology could be use in homes and offices. Make no mistake this project could have a huge effect on the wrold of GaN.”

Prof Humphreys said that once his team has cracked the method of growing GaN in this new way, QinetiQ will then take over the baton, by making it reproducible enough for commercial production.

QinetiQ will be using a growth reactor produced by TSSE, a piece of equipment with a price tag in the range of £500k and £1m. TSSE employs 77 at its Cambridge manufacturing base.

One study suggested that commercially attractive white LEDs, if fully implemented, would save up to $115bn per year in electricity in the US alone by 2015, also reducing air pollution and other waste generated by power plants.