Since Micro LED is regarded as a disruptive technology in the display field, leading domestic and foreign manufacturers such as Apple, Samsung, and BJLY Optoelectronics Technology Group have accelerated their deployment, but they generally face difficulties in wafer wavelength consistency and peak shift issues.
Traditional GaN-based blue and green LED chips are prone to color shift when the current changes. Because the Micro LED screen has a high contrast ratio and needs to switch application scenarios frequently, the large driving current changes in the process cause serious peak shift problems.
In addition, due to the small size of the Micro LED chip, wavelength sorting is difficult and the cost is too high, which brings great challenges to the wavelength consistency of the entire wafer.
How to solve the problem of wafer wavelength consistency and peak shift has become the focus of joint exploration by the entire industry. At this time, semi-polar gallium nitride (GaN) materials with a more optimized crystal orientation entered the field of view of researchers, and the name "Saphlux" was gradually familiarized by the industry.
Public information shows that Saphlux was established in 2014, mainly research and development and production of semi-polar gallium nitride light-emitting diodes. Saphlux's unique selective growth technology can directly grow semi-polar GaN materials with specific crystal orientations on a sapphire substrate, and obtain semi-polar GaN with a cost similar to that of traditional c-plane GaN. It is rare in the world that can be commercialized. GaN material company. Its co-founder Han Zhong is a professor of electrical engineering at Yale University and has been engaged in the research and development of LED materials for more than ten years.
After more than ten years of accumulation from Yale University's experimental research and development to industrialization, Saphlux has now accumulated two world-leading third-generation semiconductor technologies: semi-polar gallium nitride materials and NPQD (Nanopore Quantum Dot) Micro LED.
Compared with traditional polar gallium nitride, semipolar materials have a more optimized crystal orientation, which greatly reduces the inherent quantum confinement Stark effect (QCSE) in gallium nitride materials, eliminates the polarization field, and makes electrons The efficiency of combining with holes is greatly improved. Benefiting from this, semiconductor devices made of semi-polar gallium nitride materials can operate efficiently and at high speed in a long-wavelength, high-current environment.
In 2018, Saphlux has achieved mass production of 4-inch semi-polar gallium nitride wafers and sold them to many third-generation semiconductor companies and research institutions in Japan, South Korea, and the United States. Its application areas cover semiconductor lasers and Micro for AR/VR. LED, optical communication, power semiconductor, etc.
NPQD Micro LED is a technology released by Saphlux in 2019. According to Saphlux, NPQD refers to the quantum dot (Quantum Dot) color conversion technology based on Nanopores. Nanopores have a unique scattering effect, which can greatly increase the effective light path, improve light conversion efficiency and greatly increase the reliability of quantum dots.
Through this technology, Saphlux has developed the world's first high-efficiency quantum dot color conversion Micro LED based on nanoporous GaN material (NPQD), which solves the three key issues of red light efficiency, color and cost in Micro LEDs.
Among them, in terms of red light efficiency, the reduction of the size of the red light Micro LED of the quaternary structure will cause problems such as increase in defect density and sidewall effects, which will reduce the efficiency, and is very susceptible to changes in efficiency and wavelength due to heat.
Through the high-efficiency and high-reliability red light conversion of NPQD technology, the Saphlux team used high-efficiency blue Micro LEDs to excite red light, successfully increasing its light efficiency to 2-3 times, greatly improving the efficiency of the Micro LED screen.
In terms of color, due to problems such as the temperature distribution of the wafer material during growth, the wavelength of the green and red LED wafers has large unevenness. Previously, traditional LED chips needed to go through a sorting process to ensure that the wavelength of the light emitted by the entire screen is the same, while the size of Micro LEDs is less than 100 microns, and the sorting cost is extremely high or almost impossible to sort. The NPQD Micro LED uses quantum dot technology, and the wavelength difference of the entire wafer is less than 1 nanometer and without sorting.
In terms of cost, the Saphlux team integrated red, blue, and green NPQD Micro LEDs into the same chip, and realized the integration of three Micro LEDs on a Mini chip of more than 100 microns, which greatly reduced the chip cost and broke through the huge transfer The existing SMT method can be used to prepare Micro LED screens to solve key issues such as transfer, repair, and inspection at one time.
Due to the low cost of red light preparation and the low sorting cost, Saphlux can reduce the overall cost of Micro LED by 10 times through NPQD Micro LED technology, and truly enhance the competitiveness of the Micro LED market.
According to relevant market information, when the NPQD Micro LED technology was released, Saphlux attracted great attention from manufacturers such as Apple, Samsung, and LG. At present, Saphlux NPQD products have received orders from many Micro LED display companies around the world, and are developing in-depth cooperation with BJLY to develop the world's first quantum dot Micro LED display.
In addition to technical cooperation, Leyard had already forward-looking investment in Saphlux as early as 2017. According to related announcements by BJLY, HKLY, a wholly-owned subsidiary of the company, has invested USD 3.5 million to subscribe for 1,501,220 shares of SAPHLUX and holds a 14% stake in SAPHLUX.
At that time, BJLY pointed out that future VR/AR and smart devices will have a greater demand for portable and efficient laser projection. SAPHLUX’s semi-polar materials may be used in semiconductor lasers, forming a combination with Leyard’s existing virtual reality strategic investment. Join forces.
At this stage, VR/AR is considered to be one of the first commercialized markets for Micro LED, and BJLY's VR experience sector has launched a spin-off plan to expand its financing channels for further development. In the field of Micro LED, BJLY has also achieved a number of Micro LED commercial display products on the market. Lijing, a joint venture with Jingdian, will also officially put into production Micro LED in October.
In BJLY's view, the industrialization of Micro LED requires three essential elements: smaller and smaller LED flip chips, more and more mature mass transfer technology, and more advanced IC drive technology. At present, Lijing has the above-mentioned industrialization conditions for Micro LED, and Leyard's investment layout in Micro LED industries such as SAPHLUX will help Micro LED to accelerate its penetration in many fields.