Manufacturing method illuminates green LEDs

To produce green light, manufacturers typically apply phosphors or quantum dot materials to blue LEDs.

These materials convert short wavelength blue light, of around 450nm, to red or green wavelengths, but with a typical efficiency of between 10 to 30 per cent.

Now MicroLED technology developer Plessey Semiconductors, based in Plymouth, Devon, which builds displays for devices such as augmented reality (AR) and virtual reality (VR) systems, has produced LEDs that emit green light without the use of these colour conversion materials.

The green LEDs are produced by growing gallium nitride on silicon, in a similar way to the process used for blue LEDs, according to Dr Keith Strickland, chief technology officer of Plessey Semiconductors.

The gallium nitride is deposited in a machine called a Metal Organic Chemical Vapour Deposition (MOCVD) reactor, said Strickland.

“This system allows the deposition of highly ordered crystalline layers at the atomic level, through chemical reactions in the deposition chamber,” he said.