Using GaN as a substrate holds promise for many industries, but has immediate applications for LEDs, which Soraa manufactures. A major advancement in a commercially viable new substrate is a promising disruptive technology in the areas of higher efficiency and performance.
GaN on GaN LEDs are of particular interest because they have demonstrated much higher performance than traditional lighting technologies and thus offer the potential for major energy savings. Soraa claims to be the only LED manufacturer in the world shipping products based on superior GaN on GaN LEDs.
Currently, Soraa says this is the only ARPA-E funded LED substrate project.
According to Soraa Founder Shuji Nakamura, who is praised as the "father of LEDs" even by competitors, breakthroughs in GaN substrates can have far-reaching implications. "I have spent many decades of my life working on gallium nitride for LEDs because I believe this is a very important development and holds great promise for more energy efficient technology in lighting, power electronics and more."
Most of the LEDs of today are made by depositing GaN on non-native substrates, typically sapphire or SiC. However, many companies are now focussing their efforts on growing GaN on silicon. This is for a number of reasons. Firstly, silicon substrates are very cheap compared to the alternatives. They are also robust and come in large diameters. What's more, the infrastructure within silicon fabs could potentially allow the manufacture of GaN on silicon without having to buy more growth and other equipment. All these factors combined could reduce overall costs dramatically.
To date, adoption of GaN on GaN technology for large-scale applications has been inhibited by high costs due in part to the absence of inexpensive native GaN substrates. Creating a made-in-U.S.A. solution to the challenges of bulk GaN production will benefit the company, the LED industry, and the American consumer with more energy efficient, less expensive and more readily available components.
LEDs lend themselves well to the new substrate because it greatly enhances performance - as in the quality of the light - as a benefit in addition to energy efficiency. Because of innate physical properties of the compound, GaN on GaN LEDs can withstand higher power densities than diodes made with other substrates. This means a much brighter diode and only one LED light emitter per lamp.
Soraa says manufacturers using other substrates have to use three, four and even more to get the same brightness. Multiple sources of light within a lamp mean fuzzy shadows and not the crisp light required of an MR-16 for best use in commercial, museum or high-end consumer applications. The MR-16 lamps or bulbs are Soraa's first commercially available product.
ARPA-E, a new agency within the U.S. Department of Energy that invests exclusively in transformational energy technologies, began funding Soraa as a consortium member for this project in 2011. ARPA-E's recent decision to make Soraa the lead organisation on the project means that the firm will become the prime contractor working with ARPA-E to commercialise GaN substrate technology.
Applications for GaN substrates have the potential to reduce U.S. energy consumption by over 30%. Those same applications represent potential markets, including laser diodes and power electronics, of over $50 billion annually, according a US Department of Energy study.
"It is clear to ARPA-E that Soraa's system design and capabilities represent a breakthrough path toward the development of high-quality, low-cost GaN substrates," says Mark Johnson, ARPA-E Program Director. "We are excited to move forward in supporting their process development, crystal quality improvements, and device characterisation."
"We are pleased and honoured that ARPA-E has recognised the value and impact of Soraa's true bulk GaN substrate technology. DOE's recognition and support of this transformational technology is expected to accelerate a more energy efficient, higher performing US-based technology for LEDs and a host of additional applications," adds Mark D'Evelyn, Soraa's Principal Investigator on the project.
"Soraa is delighted to take the lead for this project and continue development of ammonothermal technology for bulk GaN substrates. This level of funding combined with the vote of confidence from the Department of Energy is a significant step forward to a future of lighting technology based on large-area, high-quality, low-cost GaN substrates," gushes Mike Krames, Chief Technology Officer at Soraa.