Plessey improves method for making green LEDs

01 Apr 2019

Higher efficiency and power for two-dimensional GaN-on-Si devices - without requiring color conversion.

Plessey, an embedded technologies developer working in microLED technology for the AR and display markets, has developed its proprietary 2D planar gallium nitride on silicon process to emit green light without the need for color conversion techniques.

To produce Green light, LED manufacturers typically apply phosphors or quantum dot conversion materials to native Blue LEDs. These materials then convert short wavelength, typically 450nm, blue light to red or green wavelengths with typically 10% to 30% efficiency.

Plessey’s native green LEDs are formed inherently using its proprietary GaN-on-Si epitaxial growth process similar to the native blue LEDs with the principal difference coming in the amount of indium that is incorporated in the quantum well structures of the LED.

Brighter than color-converted

With no color conversion losses, the native green emission is several orders of magnitude times brighter than color-converted process for microLEDs, says Plessey. With a dominant green wavelength of 530nm and a full-width, half maximum wavelength of 31nm the green is well suited for color displays. Additionally, the green emission exhibits outstanding wavelength stability versus current density, the company adds.

Mike Snaith, Chief Operating Officer at Plessey, commented, “Plessey already provides powerful, efficient native blue microLEDs and through this innovation in our growth technology, we have produced world-leading, high performance native green micro LEDs which will provide for next generation display and illuminator devices for our customers.

“Plessey’s green native GaN sources deliver higher luminance than standard blue devices fitted with green color conversion techniques. The company’s new manufacturing method for green coloured LEDs delivers world leading light output for microLED displays.”

Plessey, headquartered in Plymouth, UK, provides full-field emissive microLED displays that combine high-density RGB pixel arrays with CMOS backplanes to produce high-brightness, low-power and high-frame-rate image sources for head-mounted displays, and augmented and virtual reality systems.

The company operates leading-edge 150mm and 200mm wafer processing facilities to undertake design, test and assembly of LED products, and a comprehensive suite of photonic characterization and applications laboratories.