ESPOO, Finland, 5th of April 2022 – Picosun Atomic Layer Deposition (ALD) has played a vital role in enhancing electro-optical characteristics of micro-LEDs in research done by National Yang Ming Chiao Tung University (NYCU) in Taiwan.
The usage of dielectric films as a passivation material is a popular technique to suppress dangling bonds as well as to improve output power and external quantum efficiency in LEDs. The study conducted at NYCU compared III-Nitride micro-LEDs of different sizes with and without ALD Al2O3 passivation. The results showed external quantum efficiency enhancement of 70% for 5 µm × 5 µm micro-LEDs and 60% for 10 µm ×10 µm micro-LEDs when using ALD Al2O3 passivation.
In addition, to achieve full color display, an inkjet printing to pattern quantum dots automatically has been developed at NYCU. The solution can considerably improve the precision of color pixels and satisfy the high-resolution requirements. Picosun ALD passivation technology was successfully used for preventing the quantum dots from photo-oxidation and degradation. After a 500 hours environmental reliability test, the color gamut remained at excellent level.*
“Micro-LED technology has been the disruptive technology in the next generation displays, and more application areas are emerging its benefits being long lifetime, high power efficiency and high brightness. With quantum dot-based technology micro-LEDs can be used in applications such as virtual and mixed reality as they allow the use of single-color, blue, micro-LED chips resulting in lower manufacturing costs. Our study has proved that ALD passivation plays a key role in upcoming nanometer-scale devices”, says Hao-Chung Kuo, professor at NYCU.
“Picosun’s ALD technology has been production-proven at many prominent LED manufacturers. ALD films’ superior conformality and uniformity, and their ability to ensure reliable, pinhole-free encapsulation even at extremely low film thicknesses is a key benefit. Furthermore, the ALD process can be run at moderate temperatures”, explains Juhana Kostamo, VP, Industrial Business Area of Picosun Group.
*NTSC and Rec. 2020 standards: Color gamut 99% and 90% at 50% humidity and 50℃ temperature
NTSC: Analog television format encoding system developed by National Television Standards Committee
Rec. 2020: International Telecommunication Union Recommended standard defining various aspects of ultra-high-definition television with standard dynamic range and wide color gamut.
Vice President, Industrial Business Area, Picosun Group
Tel: +358 50 369 9565
Picosun provides the most advanced ALD (Atomic Layer Deposition) thin film coating solutions for global industries. Picosun’s ALD solutions enable technological leap into the future, with turn-key production processes and unmatched, pioneering expertise in the field – dating back to the invention of the technology itself. Today, PICOSUN® ALD equipment are in daily manufacturing use in numerous leading industries around the world. Picosun is based in Finland, with subsidiaries in Germany, USA, Singapore, Japan, South Korea, China mainland and Taiwan, offices in India and France, and a world-wide sales and support network. Visit www.picosun.com.