In September 2024, Meta unveiled Orion, a lightweight, full-color AR glasses prototype utilizing micro-LED microdisplay technology, at Meta Connect 2024. It features multiple sensors and silicon carbide waveguides. Mark Zuckerberg called it "the best AR glasses in the world." In Meta's official promotional video, NVIDIA CEO Jensen Huang praised the AR glasses, saying, "The display and color are great, and the eye-tracking technology is fantastic."
This new benchmark product has once again brought the key micro-display technology behind smart glasses to the forefront of technological exploration. Micro LED, representing the next generation of display technology, has demonstrated its superior performance in large-size displays and is gradually shining in the micro-display field. TrendForce estimates that by 2030, Micro LED technology will account for 44% of the application in AR glasses.
Micro LED displays possess unparalleled advantages in brightness and reliability compared to traditional technologies; however, it will take time for them to move from prototypes to large-scale commercial use. my country's industry, academia, and research communities are tirelessly working together to promote the technological advancement and industrialization of Micro LED displays.
Recently, domestic enterprises and university research teams have joined forces to achieve the latest breakthrough in key technologies of Micro LED microdisplays, and published important results in core international academic journals.
Good news keeps coming from the research of domestic Micro LED microdisplays . To overcome the bottleneck of full-color Micro LED microdisplays, in September this year, a research team from Hunan University, in collaboration with Hunan Normal University, Norvision Technology, and Crystal Optoelectronics, published a paper in the academic journal Advanced Materials on a full-color Micro LED integration process based on quantum dot color conversion pixels. They also fabricated a 0.39-inch Micro LED full-color microdisplay chip with an ultra-high brightness of 400,000 nits and an ultra-high resolution of 3300 PPI.
Image source: Advanced Materials
A month later, the research team from Hunan University, together with collaborators such as Novis Technology, Crystal Optoelectronics, and Digital Light Core, published their research results and solutions in the renowned academic journal Light: Science & Applications, addressing the challenge that existing Micro LED microdisplays cannot meet the requirements for practical applications in terms of brightness and uniformity.
Image source: Light: Science & Applications
The joint team has successfully developed IC-grade GaN-based Micro LED wafer manufacturing technology, including large-size, high-quality silicon substrate Micro LED epitaxial wafer fabrication process, misaligned bonding integration technology, and atomic-level sidewall passivation technology. They have achieved a green Micro LED micro-display module with the highest publicly reported brightness of 10 million nits on a silicon substrate GaN epitaxial wafer.
Behind these two Micro LED microdisplay research achievements lies the integration and collaboration of the most cutting-edge technologies in China's LED industry. Among them, LONGi Optoelectronics provided the industry's leading large-size silicon substrate Micro LED epitaxial wafers.
Large-size silicon substrate epitaxy is the cornerstone of Micro LED microdisplay technology development . Currently, there are two main technical routes for Micro LED epitaxial wafer growth and subsequent chip manufacturing processes: one uses 4/6-inch sapphire substrates for epitaxial growth; the other uses 8-inch or larger silicon substrates for Micro LED epitaxy. As micron-level pixel Micro LED microdisplay products enter IC-like processes, the large-size silicon substrate GaN-based Micro LED epitaxy technology route is gradually demonstrating superior characteristics such as high substrate removal yield, high CMOS bonding yield, large size, low cost, and low warpage.
It is foreseeable that the further maturation of silicon substrate epitaxy technology will become a key driver for the industrialization of Micro LED microdisplays.
Large-size silicon substrate epitaxy technology is more in line with the current development trend of Micro LED applications.
Despite its longer development history and higher maturity, sapphire substrate GaN LED technology has become the mainstream in the general lighting field. However, a few LED companies at home and abroad have already grasped the industry trend and seen the huge potential of large-size silicon substrate epitaxy in the field of Micro LED with a longer-term vision, taking the lead in R&D. LONGi Optoelectronics is a pioneer in silicon substrate Micro LED epitaxy technology in China.
As one of the few domestic LED companies that focuses on silicon substrate GaN technology, LONGi Optoelectronics has successfully applied its silicon substrate GaN-based LED technology to mobile phone flashlights, mobile lighting, automotive lighting and other fields. It continues to upgrade its silicon substrate GaN-based LED epitaxial products from 4 inches to 8 inches and 12 inches, greatly optimizing technical performance and cost.
As early as 2018, LONGi Optoelectronics took the lead in China to carry out research and development of GaN-based blue, green and red Micro LED epitaxial technology on large-size silicon substrates.
In 2020, LONGi Optoelectronics launched its 8-inch silicon substrate InGaN red light epitaxy technology; in 2021, LONGi Optoelectronics fabricated a silicon substrate InGaN red, green, and blue tri-color Micro LED array with a pixel density of 1000 PPI.
Crystal Optoelectronics GaN-based RGB Micro LED Array on Silicon Substrate
In 2022, LONGi Optoelectronics made a breakthrough in the key technology of epitaxial growth of InGaN-based three-color Micro LEDs on 8-inch silicon substrates and successfully fabricated a 5-micron pitch Micro LED three-color array.
In 2023, LONGi Optoelectronics released its achievements in epitaxial technology for a full range of red, green, and blue three-color Micro LEDs based on 12-inch silicon substrate InGaN, laying the foundation for improving efficiency and reducing costs of Micro LEDs and continuing to promote the development of micro-display technology.
Crystal Optoelectronics' 12-inch silicon substrate red, green, and blue InGaN-based LED epitaxial wafer rapid test EL lighting effect
Currently, LONGi Optoelectronics has acquired full-color silicon substrate GaN LED epitaxial technology in the 365-650nm range and has developed 4-12 inch silicon substrate GaN-based red, green, and blue Micro LED epitaxial wafers. It has provided high-quality epitaxial wafers with standard thickness 8-inch CMOS matching to research institutions and enterprises worldwide.
For applications such as multi-pixel matrix automotive lights and automotive HUDs, LONGi Optoelectronics has developed a blue Micro LED epitaxial structure that can achieve an external quantum efficiency of over 20% at 1000 A/cm².
In the future, LONGi Optoelectronics will continue to deepen its expertise in the field of large-size silicon substrate GaN-based Micro LED epitaxial technology, and will also collaborate more closely with midstream and downstream partners to explore and promote the industrialization of Micro LED microdisplay technology in my country.
Summarize
The LED industry is rapidly moving towards the Micro LED era. Driven by cost and yield, upgrading to large-size silicon substrate Micro LED epitaxial wafers has become an important development trend in the industrialization of Micro LED.
Against the backdrop of global companies actively researching and exploring the application potential of Micro LED technology in the micro-display field, LONGi Optoelectronics has continuously improved its silicon substrate Micro LED epitaxial technology, contributing to the leading achievements of domestic Micro LED micro-display technology. In the future, LONGi Optoelectronics will continue to work with its Chinese LED industry colleagues to overcome technical challenges in Micro LED and lead the Chinese LED industry to the forefront of Micro LED technology.
