Everybody was talking about the GaN microdisplay Leti unveiled at Display Week 2017, held in Los Angeles on May 23–25. And for good reason: The microdisplay is the first ever to achieve a resolution of 873x500 for a 10-micron pixel pitch.

The advance, a joint effort between Leti and the III–V Lab, was made possible by combining several technological innovations. First, a GaN micro-LED matrix with the desired features was developed. A patented self-aligned fabrication technique was developed to produce the matrix. The matrix was then assembled with an active CMOS matrix (an integrated circuit whose role is to run each LED individually to write the image). Here again, the researchers had to develop a specific hybridization technique to assemble the matrices. Metal microtubes are positioned on the active matrix so that metal dots deposited at each LED can be inserted into the tubes by simple mechanical pressure at ambient temperature.

The next steps will be to take the technology from monochromatic to color and continue work on a very innovative, alignment-free fabrication method that will make it possible to reduce the pixel pitch to just three microns. "The method, also unveiled at Display Week, eliminates the hybridization step, which is currently an obstacle to further reducing pixel pitch," said a researcher. Stay tuned for further developments.