Aledia is the best funded company (200M Euro) developing 3D nanowire or nanoLEDs with a new 8-inch GaN-on-Silicon fab operational since September 2025 in France. The company says their nanowire yield is now at 99.999%, so very high.
In their approach, it is the size of the nanowire that determines the output wavelength (smaller for red and larger for blue). This allows the company to grow red, green and blue nanowires in a single growth process to create spatially-defined full color microLED displays. And it will allow the microLED wafers to be wafer bonded to the CMOS backplane.
For AR glasses (and optical interconnects), Aledia has an advantage in its ability to shape the output cone angle. They can get fairly narrow cones which leads to much better efficiency for coupling into the waveguide (or connecting to fibers for datacom).
To achieve a narrow wavelength, they arrange the nanowires in a regular lattice to form a photonic crystal structure. A photonic crystal effect can be initiated with a central nanowire and surrounding nanowires, but the effect becomes much strong as the extent of the periodic array increases. It is believed that this arrangement is creating a high Q cavity in the X and Y direction, but not in the Z direction, which thus allows the light to “leak out.” This effect also allows the light to exit at a specifically designed angle. Aledia can model a range of nanowire diameters and pitches to optimize the wavelength and emission angle.
For the hard to make red GaN devices, they have achieved a 2.4X increase in far filed illumination compared to a Lambertian microLED in a +/- 20-degree FOV. Their goal is to achieve a 5X increase.
A monochrome pixel is created from a number of nanowires. Multiple nanowires are connected in parallel to form a pixel. This allows the sub-pixel to still light up even if there are some failed nanowires. For a sub-pixel pitch of 2.5 microns for example, perhaps 16 nanowires are connected in parallel.
At Display Week, they were highlighting the demonstration of all three colors fabricated together showing the Aledia logo. Each part of the logo was driven as a single pixel, so no CMOS backplane as they feel that step is unnecessary at this stage while they work on improving efficiency.
CEO Pierre Tchoulfian noted that for monolithic devices, testing of the green (530 nm) wafer reveals the median EQE is around 3.89% and for the blue (450 nm), the median EQE is around 4.14%. Red is now their current focus area.
In the full-color demo, these blue and green emission points seem quite different, leading to the poor 47% DCI-P3 gamut coverage.
