Korean micro-LED manufacturer, Lumens, announced in January, the development of R-G-B micro-LEDs grown in a stack, on a single wafer / substrate (aka monolithic). The benefits of this approach include reducing the transfer process by two-thirds, reducing costs, and increasing productivity.
The first applications for this technology are the micro-LED display markets, including TV, AR, and VR. Micro-LEDs typically emit a single color, with each color grown separately on different epitaxial wafers. Lumens has grown all three colors vertically stacked on a single wafer.
Micro-LED displays are typically made with millions of single-color micro-LEDs, and it takes one of each of the three colors to make a single pixel. That is three transfer processes per pixel. With Lumen’s R-G-B micro-LED, it will only take one transfer process per pixel, reducing processing time by 2/3rds.
Lumens accomplished this by changing the material used to make its red emitter, from gallium arsenide (GaAs) to indium gallium nitride (InGaN). The InGaN matches the material that the blue and green emitters are made from, allowing all three colors to be grown vertically stacked on a single wafer. It is common for innovations adopted in the display industry to eventually become adopted by the general lighting industry.
More information is available here.
Images: Lumens
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