We’re pleased to feature Sundiode, stacked-RGB microLED microdisplays developer, in our latest MicroLED Industry Association spotlight series.
We spoke with James Kim, Sundiode's CEO and co-founder, to learn more about the company's technology, business, achievements and goals.
Can you introduce your company and technology?
Sundiode is a company in Silicon Valley developing microLED technologies. Sundiode uniquely focuses on utilizing 3D fabrication of LED devices that allows vertical stacking of LEDs, where the resultant multiple junctions advantageously lend themselves to next generation microLED pixel technology. Applied to displays, the technology allows full-color RGB microdisplays with ultra-high resolution and exquisite display quality. Sundiode is a fabless company and has been developing the Stacked MicroLED device technology in Campbell, CA, in the US and is commencing making commercial successes.
Sundiode’s focused approach is based on enabling vertical stacking of LEDs, building upon the already well-established InGaN and AlInGaP epitaxial technologies. The resulting vertically stacked devices can be advantageously utilized in many areas, including AR displays for consumer and defense applications, wearable devices, beauty and health/fitness sensing, and medical diagnosis/treatment that requires high spatial resolution light illumination and detection of light with multiple light wavelengths.
Can you say why you joined the MicroLED Association and what you hope to achieve?
Sundiode believes the Stacked MicroLED technology can benefit the microLED industry in the areas of display and light illumination applications. In turn, by thoroughly understanding the development of the microLED industry through the platform, Sundiode seeks to benefit from the member companies in the association who can offer critical technology benefits to Sundiode. The MicroLED Association is a great platform where such interactions can occur, and Sundiode aims to actively engage itself in industry discussions.
What is your biggest challenge, and success to date in the microLED industry?
Sundiode has been at the forefront of promoting the Stacked MicroLED device architecture. Sundiode was the first company to show a Stacked-RGB microLED display prototype. In the industry where the established norm was the lateral, side-by-side placement of picked-and-placed subpixels in a display pixel, successfully demonstrating multiple-junction pixel devices and making a (monolithic panel) display thereof were a grand challenge and a proud success moment. Prior, the industry saw the need for stacked subpixels but was skeptical of the possibility. Sundiode showed that the vertically stacked LED junctions can be fabricated (in a monolithic full-color display panel with “zero” pick-and-place) to constitute Stacked-RGB pixels fully integrated into a CMOS display backplane, and achieving the success required overcoming challenges hitherto unconsidered.
Sundiode is currently developing and marketing sub-10 µm pixel displays for various applications including in microdisplays. Sundiode’s Stacked MicroLED device technology offers many advantages over the side-by-side subpixel technology, including higher resolution and form factor reduction, excellent chromaticity performance, and manufacturing complexity/overhead reduction. These are crowning achievements that allow Sundiode to also expand to non-display areas such as beauty and health sensing and clinical medical treatment.
Can you detail your latest prototype/demonstration?
At the SID Display Week 2023, we showed our Stacked-RGB MicroLED display with 200 PPI resolution, where the display was very well received and awarded the Best Prototype Award. The aim of the demo display was to convincingly show the operation of a monolithic display panel consisting of stacked microLED subpixels driven by a CMOS display backplane. Although the significance for Sundiode was the successful demonstration of the operation of multiple junction pixel devices, the demo further indicated the stunning display quality (brightness and “crispness” as commented by the judges and industry experts) due to the Stacked MicroLED device architecture.
Since 2023, Sundiode has refined its technology and designs for custom-building of displays which generally have a pixel pitch under 10 µm. By doing so, Sundiode is solidifying its footing in the Stacked MicroLED microdisplay area, including in performance and manufacturing processes. The microdisplays that will debut soon will be utilized in the areas of defense (situational awareness apparatus). Further, Sundiode identifies light extraction from a pixel as the area most amenable to a meaningful performance increase and have worked to develop light-extraction enhancement technologies. A consequence of the focus on light extraction is the Sundiode’s engagement of the LCoS light source development because the Stacked MicroLEDs can achieve true uniformity of locally dimmable LCoS light sources.
How do you see microLEDs changing the display industry in the next 5–10 years?
Sundiode sees microLEDs dominating the technology for microdisplays for AR. There is, however, stiff competition from OLED displays that continue to improve, especially with respect to display resolution and device robustness. Additionally, LCoS microdisplays that utilize microLED light sources are being touted to be suitable for AR perhaps more quickly than microLED displays. Sundiode, for its part, intends to also participate in the latter since there, the Stacked MicroLEDs remain best suited.
While AR is the driver of technology innovation in microLEDs, Sundiode also sees application areas such as health and beauty, clinical applications, and defense industry as areas of growth in the microLED industry. Sundiode is looking to apply itself in these areas in the coming years.