LETI First to Present Results in LED Pixelisation & Record High Resolution for Micro Displays

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Leti, a research institute of CEA Tech, today announced it has developed a μLED fabrication process to create high-resolution arrays at 10-micron pitch. That pixelization and the 873 x 500 resolution that are enabled by the new process exceed state-of-the-art technology

Designed for micro-display applications such as augmented-reality or virtual-reality tools and wearable devices, the blue or green GaN/InGaN µLED arrays use Leti’s proprietary self-aligned technology. That process is key to achieving such a small pixel pitch. A combination of several damascene metallization steps used to create a common cathode is also expected to provide good thermal dissipation and prevent voltage drops within the micro-LED matrix. Electro-optical measurements showcase record efficiency and brightness exceeding requirements for device integration.

The results were presented Feb. 2 at SPIE Photonics West in San Francisco in a paper: “Processing and Characterization of High-Resolution GaN/InGaN LED Arrays at 10-Micron Pitch for Micro-Display Applications”.

“Leti’s self-aligned process allows the creation of high-resolution µLED matrices with a reduced pixel pitch of 10 µm and paves the way towards even smaller pitches for next-generation devices,” said Ludovic Dupré, one of the paper’s authors. “In addition, the use of the damascene metallization process of the cathode, which also is a new process developed at Leti, is a breakthrough compared to previous demonstrations of micro-LED matrices. The common cathode indeed fills the whole volume between the micro-LEDs and provides metallic spreading of electrical current between them, as well as thermal dissipation. These results are promising for integrating a micro-LED matrix in micro-display devices by hybridization on CMOS active matrices, and first prototypes are currently being tested.”

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