InGaN/GaN µLEDs are a promising candidate to visible optical communication applications thanks to their high luminosity and high bandwidth. High data rate are reachable by using them as an array to realize parallel communication. To optimize their integration, we propose a CMOS compatible process to make the µLEDs directly on top of an ASIC and to use them as emitter and fast photodetector. We have demonstrated functional µLEDs on a 200mm silicon substrate and frequency characterization were performed for both emission and reception.
Efficient Light Emitting Diodes (LED) with a wide color gamut for high-resolution RGB display applications is still a challenging objective for state of the art technologies. The current industrial technology compromises the narrow RGB peaks emission with device efficiency. In this work, we demonstrate a CMOS compatible monolithic hybrid approach the fabrication of GaN Blue micro-LED co-integrated with Green or Red top emitting OLED on 8’’ GaN epitaxy on Si, with LED sizes as low as 5µm. This approach fulfills the need of a good color purity, while taking advantage of the best of both technology efficiencies and emission width.
We introduce an original approach for an extended Head Up Display solution. This configuration is based on the projection of images directly on the windshield of a vehicle, allowing the display of various information around the user viewing axis, as a peripheral dashboard. We highlight that this solution is only effective if we can manage both directivity and diffusivity of the reflected light. We introduce for that purpose two technological options. A pragmatic one allows us to evaluate at short term the HUD behavior. Another proposes an original approach with a manufacturing process based on the etching of a deep cube corner cavity in a composite silicon wafer that incorporates a diffuser surface. We demonstrate both technological options and give some perspectives for future works.
We report high resolution (873 x 500), active-matrix, GaN-based LED microdisplays with a pixel pitch of 10 μm. They exhibit the highest resolution for the smallest pixel pitch ever reported for GaN microdisplays. High-density GaN μLED arrays were first patterned at 10-μm pitch on sapphire substrates. Arrays were then hybridized on CMOS active-matrix using the microtube technology. Blue and green monochrome prototypes have been realized. Full video, high-resolution images have been obtained. The performance of these GaN-based microdisplays make them suitable for a wide range of applications from augmented reality and head-up displays to pico- and compact projectors.
We report the fabrication process and characterization of high resolution 873 x 500 pixels emissive arrays based on blue or green GaN/InGaN light emitting diodes (LEDs) at a reduced pixel pitch of 10 μm. A self-aligned process along with a combination of damascene metallization steps is presented as the key to create a common cathode which is expected to provide good thermal dissipation and prevent voltage drops between center and side of the micro LED matrix. We will discuss the challenges of a self-aligned technology related to the choice of a good P contact metal and will present our solutions for the realization of the metallic interconnections between the GaN contacts and the higher levels of metallization at such a small pixel pitch. Enhanced control of each technological step allows scalability of the process up to 4 inch LED wafers and production of high quality LED arrays. The very high brightness (up to 107 cd.m-2) and good external quantum efficiency (EQE) of the resulting device make these kind of micro displays suitable for augmented reality or head up display applications.
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