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Breakthrough in microLED development as red light is achieved
In the summer of 2023, Polar Light Technologies achieved a highly controlled blue light from microLEDs in the shape of small pyramids for the first time. Just three months later they also managed to achieve green light. With an ambition to produce red light, the most difficult to achieve, before the end of 2024 they did just that, and presented red light the 18th of December, setting a new course for the global display market.
Light-emitting diode technology, or LED technology, includes a semiconductor device that emits light when current flows through it. The color of the light is determined by the energy required for electrons to cross the band gap of the semiconductor. In these small pyramid shaped microLEDs (μLED), the diodes have unique properties with small dimensions (down to microns), high brightness and efficiency, and will eventually phase out older technologies in existing displays.
“MicroLEDs can fit 600 million pixels on a fingertip, making them particularly important and applicable for AR-based applications such as HUDs (head-up displays) and HMDs (head-up displays/smart glasses)”, says Per-Olof Holtz, CSO and founder of Polar Light Technologies.
Polar Light Technologies, founded in 2014, is based on research into nanostructures in semiconductor materials at Linköping University. They aim to produce state-of-the-art microLEDs that are efficient, less energy-consuming and better-functioning than today’s displays, especially within AR.
The microLEDs are composed of pyramid shapes that are built with a unique bottom-up approach, a technology that comes with some great advantages. In order to produce blue, green and red microLEDs from the same material, the eventual strain in the lattice-mismatched InGaN/GaN structures needs to be reduced, which this structure does. It also allows for the unique possibility to integrate the frontplane with a backplane without etching, meaning performance is maintained in smaller dimensions, since no etching damage could occur. The pyramid composition also enables sub-µm LEDs – nanoLEDs, and is easier to manufacture and integrate with CMOS and TFT.
Polar Light Technologies has worked with RISE for several years, accessing RISE’s cleanroom laboratories in Kista (Electrum) and Lund (ProNano), as well as highly skilled researchers.
“The collaboration with the RISE research team and being able to use the facilities in Lund and Kista has been a game changer for us. The support they have given us, and access to the equipment, especially the MOCVD tool at ProNano, has helped us with a much higher quality in the quantum structures of our microLEDs. And has eventually led to us achieving the red light”, says Oskar Fajerson, CEO at Polar Light Technologies.
The red color is difficult to achieve due to challenges in the material properties. There are alternatives to be able to reach a red color, but not without a loss in efficiency, manufacturability or capability to integrate with other material systems. However, through the innovative pyramidal structure, Polar Light Technology managed to realize the red light.
“This breakthrough is the result of years of hard work and rigorous research and development, enabling spatial computing and next-generation panel displays”, says Oskar Fajerson, CEO at Polar Light Technology.
