Emerging Trends in China’s Micro LED Industry
In recent years, government funding and incentives have fostered the emergence of numerous specialized semiconductor teams and start-ups in China. The growth of key industries like photovoltaics and new energy vehicles has provided supply chain opportunities, fueling rapid advancements in the compound semiconductor market. As a result, the competitive landscape is expected to shift dynamically.
The compound semiconductor industry’s outlook for 2024 is filled with questions: How can the industry overcome geopolitical challenges and technological bottlenecks? To explore these issues, Compound Semiconductor magazine has launched the “2024 Outlook” series, featuring insights from industry experts and executives. In this series, we interviewed Dr. Zhuang Yongzhang, CEO of Raysolve Optoelectronics Technology (Suzhou) Co., Ltd., who shared his unique perspectives.
Interviewee: Dr. Zhuang Yongzhang
Dr. Zhuang Yongzhang, founder and CEO of Raysolve, graduated from Hong Kong University of Science and Technology (HKUST) under the mentorship of Professor Kei May Lau, a leading figure in optoelectronics and Micro-LED. With over 17 years of experience in semiconductor process and material research, Dr. Zhuang specializes in third-generation semiconductors and Micro-LEDs. His team has successfully developed several groundbreaking ultra-high-resolution Micro-LED micro-display chips. Dr. Zhuang has published over 40 papers in international journals and prestigious conferences and has applied for more than 130 domestic and international patents. He has been recognized as a leading talent in Suzhou Industrial Park and a Gusu leading talent.
Raysolve Optoelectronics Technology (Suzhou) Co., Ltd.
Raysolve Optoelectronics Technology (Suzhou) Co., Ltd. is a high-tech enterprise focused on the design, process, and monolithic full-color technology development and production of Micro-LED micro-display CMOS chips. The company’s core team originates from the Department of Electronic Engineering at HKUST and possesses years of experience in cutting-edge optical chip design and manufacturing. Raysolve has independently developed monolithic full-color Micro-LED micro-display chips based on quantum dot lithography, establishing a leading full-color Micro-LED display technology and solutions. The company is dedicated to overcoming the core bottlenecks of near-eye display technology and accelerating the commercialization of consumer AR applications.
Questions & Answers
UV-LED and Mini/Micro-LED are two major growth points in the nitride optoelectronics industry, attracting significant interest from both the industry and capital markets. However, there are still many challenges in technology, application, and market aspects. Could you share your views on the future development trends of UV-LED and Micro-LED technologies and their commercialization?
In recent years, the Micro-LED micro-display industry has seen a steady stream of good news in technology development, product launches, and investments, accelerating the commercialization of Micro-LEDs once again.
On the upstream side, wafer manufacturers are developing larger-sized Micro-LED wafers, such as 8-inch and 12-inch wafers. Equipment manufacturers are introducing tools capable of larger-scale production and testing of Micro-LEDs. In the midstream, multiple chip manufacturers have launched small-sized, high-resolution, high-brightness monochrome or full-color micro-displays and display modules to meet the application needs of XR and other wearable devices. Downstream and at the end-user level, smart glasses products, represented by AR glasses, are constantly emerging.
One of the hottest topics currently is how to achieve monolithic full-color displays with Micro-LED micro-displays. Due to the limitations of epitaxial growth, efficient single-layer gallium nitride epitaxy can only emit monochromatic light of a specific wavelength, which has resulted in most Micro-LED micro-display chips being monochrome. In 2023, quantum dots, which won a Nobel Prize, pushed LED displays into the spotlight. Quantum dots enable precise color representation and a more perfect color gamut for display products. In Micro-LED applications, quantum dot color conversion effectively reduces process complexity and drives technological advancement.
Using UV LED or blue light LED with quantum dots can achieve colorization on a single display. For instance, using UV Micro-LED requires the excitation of red, green, and blue quantum dots to achieve RGB color mixing. However, this approach is generally less efficient due to the low light efficiency of UV LEDs and blue quantum dots. Alternatively, using blue Micro-LEDs with red and green quantum dots combines the high efficiency of blue Micro-LEDs with red and green quantum dots to achieve high-efficiency full-color displays.
There are two primary methods for achieving full-color displays with quantum dots: quantum dot inkjet printing and quantum dot lithography.
Quantum dot inkjet printing utilizes nozzles and airflow to deposit quantum dot materials dissolved in organic solvents onto UV or blue Micro-LEDs. The line width is determined by controlling the dosage and droplet size of the quantum dot materials. This technique may be suitable for mass production of large-sized devices but is not ideal for smaller sizes. Quantum dot printing faces significant challenges in scalability and yield, with reduced efficiency as chip resolution increases and alignment difficulties as pixel size decreases below the nozzle’s physical limit. Furthermore, diffusion of the organic solvent causes low printing accuracy and severe crosstalk, impacting display quality.
The alternative approach, quantum dot lithography, exemplified by Raysolve, involves a quantum dot photoresist solution that integrates standard quantum dot and photoresist materials through innovative technology. This method maintains high conversion efficiency while retaining the high-resolution characteristics of photoresists, achieving a quantum dot photoresist thickness of less than 2 micrometers. The solution meets Micro-LED’s requirements for ultra-small pixel sizes while ensuring high absorption efficiency, effectively converting blue light into green and red light for full-color chips. The quantum dot color conversion method avoids the inherent efficiency issues of native red light. Additionally, lithography is a standard semiconductor process with higher precision and efficiency, making it highly feasible for mass production. Raysolve has already developed several full-color micro-display products using 8-inch semiconductor processes, including 0.11-inch and 0.22-inch full-color micro-displays with a pixel density of up to 7,200 ppi, achieving over 150,000 nits of brightness and 108.5% DCI-P3 color gamut coverage, showcased at the 2023 SID Display Week in the United States. These products have garnered significant industry recognition and attention.
While many companies are developing Micro-LEDs, and some have demonstrated prototypes of full-color Micro-LED micro-displays, no company has yet achieved true mass production of full-color Micro-LED chips. Multiple technological pathways for achieving full-color Micro-LEDs are being validated by the industry and market, each with unique challenges. However, the fundamental bottlenecks across various stages remain consistent: precision, yield, efficiency, and cost. These issues are interrelated and progressively linked. The foundational requirement for Micro-LED display technology is precision; without high precision, it is difficult to achieve high-performance Micro-LED displays. Under the premise of ensuring precision, yield and efficiency are critical factors in reducing costs and are prerequisites for large-scale commercialization of Micro-LED technology. Currently, most aspects of Micro-LED full-colorization are still focused on improving precision, with a significant distance yet to cover before advancing to stages focused on yield and efficiency.
The prospects for Micro-LED applications in AR displays are promising, but many technical hurdles remain before achieving the ideal outcomes desired in AR. As domestic Micro-LED micro-display chip players like Raysolve begin to make their mark in the market, this sector is poised to enter its next growth phase.
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