GaN-on-GaN technology is ‘LED 2.0’ says blue LED inventor

Shuji Nakamura, the inventor of the blue LED, told LuxLive last week that the future of LEDs lies in GaN-on-GaN technology, which offers the potential for better colour rendering, higher efficiency, longer lifetime and more ‘lumens per dollar’.

Nakamura developed blue and green LEDs in the 1990s, making it possible to produce white light from LEDs for the first time, and kicking off a lighting revolution that continues today.

Since then he co-founded LED lamp maker Soraa, which uses violet chips made of gallium nitride on a gallium nitride substrate (GaN on GaN), rather than a conventional sapphire or silicon carbide substrate.

Nakamura described GaN on GaN as ‘LED 2.0’, explaining that it has the advantage of having very few crystal defects compared to normal LEDs. ‘We can operate these at high current, high temperature, and reliability is very good,’ he said.

The technology allows current density to be increased by a factor of 10, allowing huge increases in light output, Nakamura said.

He predicted that GaN-on-GaN LEDs ‘will overtake first-generation LEDs in the near future, reducing the total cost of lighting by decreasing “dollar per lumen”, thus accelerating the adoption of LED technology’.

When asked if he realised the revolution he would unleash when he first invented the blue LED, Nakamura said he saw a ‘huge market’ once blue and green LEDs had been created, because now LEDs ‘could be white or any kind of colour’.

‘I expected the speed [of development] would be very fast,’ he said.

He also predicted that blue LED products will hit efficacies of 250 lm/W in the next few years. ‘I think some companies already have that at peak [in lab conditions] but under operating conditions it’s half that. I would expect that under operating conditions in two to three years,’ he said.

Nakamura was lukewarm about the future of OLED, pointing to lifetime as an issue with the technology, but he sees big potential in laser lighting because of the potential to massively increase current density.

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