Paper accepted in Journal of Physics: Photonics!

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Abstract

Micro LED can play an important role in the future generation of smart displays. They are found very attractive in many applications, such as maskless lithography, biosensor, AR/MR etc., at the same time. A monitor that can fulfill saturated color rendering, high display resolution, and fast response time is highly desirable, and the micro LED-based technology could be our best chance to meet these requirements. At present, semiconductor-based RGB micro LED chips and color-conversion enhanced Micro LEDs are the major contenders for the full-color high resolution displays. Both of the methods need revolutionary ways to perfect the material qualities, fabricate the device, assemble the individual parts into a system. In this roadmap, we will highlight the current status and challenges of the micro LED-related issues, and discuss the possible advances in science and technology that can stand up to the challenges. The innovation in epitaxy, such as the tunnel junction, the direct epitaxy and nitride based quantum wells for red and ultraviolet, can provide critical solutions of the micro LED performance in various aspects. The quantum scale structure like nanowire or nanorod can be crucial for the scaling of the devices. Meanwhile, the color conversion method, which uses colloidal quantum dots as the active material, can provide a hassle-free way to assemble a large micro LED array, and emphasis on the full color demonstration via colloidal quantum dots. These quantum dots can be patterned by porous structure, inkjet or photo-sensitive resin. In addition to the micro LED devices, the peripheral components or technologies are equally important. Microchip transfer and repair, heterogeneous integration with the electronics and the novel 2D material cannot be ignored or the overall display module will be very power-consuming. The augmented reality is one of the potential customer for our micro-LED displays and the user experience so far is limited due to lack of the truly qualified display. Our analysis showed the micro LED is on the way to address and solve the current problems, such as high loss optical coupling and narrow field of view. All these efforts are channeled to achieve an efficient display with all ideal qualities that meet our most stringent viewing requirements and expect it to become an indispensable part of our daily life.