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Etude des caractéristiques électro-optiques de micro-LED GaN pour application aux micro-écrans haute-luminance

Abstract : The display industry is facing a fast transformation. New technologies (mainly LCD and OLED) have faded-out the cathode ray tube of the 20th century and lead to new applications (3D, flexible and transparent displays). A very particular type of display has recently emerged to address new markets, such as augmented reality: micro-displays. They can be defined as having a diagonal of around 1 inch or less. One important goal of these micro-displays is to deliver the same image quality as conventional, larger-size displays. Strong challenges arise in terms of definition, compactness, consumption and brightness. To address these, LED micro-displays are currently being studied. In a LED micro-display, a 2D-array of micro-LEDs is fabricated, where each LED acts as a single pixel of a whole image. The main objective of this thesis work is to study the specifics of Gallium Nitride (GaN) micro-LEDs arrays for micro-display applications.Our investigations have been carried out focusing on three major areas of study. Increasing LED efficiency through the study of our fabrication process was the first goal. By improving P metal and enhancing P-GaN electrical performances, we were able to increase efficiency of micro-LED by a factor of 10.The influence of size-reduction on the performances of LEDs have then been thoroughly investigated. As LED size decreases, its maximum efficiency drops. Non-radiative recombinations occurring at the edges of the LED were found to be the main origin. We have then studied LEDs, not as a single diode, but as a dense 2D array of micro-LEDs allowing image display, and optical and electrical spread have been investigated. Furthermore, optical cross-talk has been studied and fabrication was changed to address this issue. New structures have also been suggested to improve light extraction efficiency, which is one of the main hindrance towards high-efficiency micro-LEDs. Finally, state-of-the-art, blue and green, active matrix micro-LED displays have been obtained and characterized during the course of this thesis work.
Keywords : GaN Micro-LED Display
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https://tel.archives-ouvertes.fr/tel-01868252
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Submitted on : Wednesday, September 5, 2018 - 11:41:53 AM
Last modification on : Thursday, June 11, 2020 - 5:04:07 PM
Long-term archiving on: : Thursday, December 6, 2018 - 3:06:56 PM

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OLIVIER_2018_diffusion.pdf
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François Olivier. Etude des caractéristiques électro-optiques de micro-LED GaN pour application aux micro-écrans haute-luminance. Micro et nanotechnologies/Microélectronique. Université Grenoble Alpes, 2018. Français. ⟨NNT : 2018GREAT019⟩. ⟨tel-01868252⟩

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