Detectors & Imaging

Leti develops smaller-pixel-pitch, highest-resolution microdisplays

Feb. 7, 2017

Leti developed a micro-LED (μLED) fabrication process to create displays with an 873 x 500 resolution.

Research agency Leti (Grenoble, France), an institute of CEA Tech, has developed a micro light-emitting diode or micro-LED (μLED) fabrication process to create high-resolution arrays at 10-micron pixel pitch. Leti says that the 873 x 500 resolution enabled by the new process exceeds state-of-the-art technology.

Designed for microdisplay applications such as augmented-reality or virtual-reality tools and wearable devices, the blue or green gallium nitride/indium gallium nitride (GaN/InGaN) µLED arrays use Leti's proprietary self-aligned technology that 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 February 2 at SPIE Photonics West 2017 in San Francisco in a paper entitled "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."

SOURCE: Sarah-Lyle Dampoux of Mahoney Lyle; http://www.leti.fr/en

About the Author

Gail Overton | Senior Editor (2004-2020)

Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.