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Low-Cost GaN Substrates

ARPA-E Award: 
Fremont, CA
Project Term: 
02/17/2014 to 05/17/2015
Project Status: 
Technical Categories: 
Critical Need: 
Power semiconductor devices are critical to America's energy infrastructure--all electronics, from laptops to electric motors, rely on them to control or convert electrical energy in order to operate properly. Unfortunately, the performance and efficiency of today's dominant power semiconductor device material, Silicon, suffer at higher power levels and higher temperature. This results in substantial loss of efficiency across our energy infrastructure. Innovative new semiconductor materials, device architectures, and fabrication processes promise to improve the performance and efficiency of existing electronic devices and to pave the way for next-generation power electronics.
Project Innovation + Advantages: 
Soraa will develop a cost-effective technique to manufacture high-quality, high-performance gallium nitride (GaN) crystal substrates that have fewer defects by several orders of magnitude than conventional GaN substrates and cost about 10 times less. Substrates are thin wafers of semiconducting material needed to power devices like transistors and integrated circuits. Most GaN-based electronics today suffer from very high defect levels and, in turn, reduced performance. In addition to reducing defects, Soraa will also develop methods capable of producing large-area GaN substrates--3 to 4 times larger in diameter than conventional GaN substrates--that can handle high-power switching applications.
Potential Impact: 
If successful, Soraa will produce cost-effective, high-quality, high-performance GaN substrates for use in a variety of high-power applications, including motor drives and efficient lighting.
Advances in power electronics could facilitate greater adoption of electric vehicles, which in turn could help reduce U.S. oil imports.
More efficient power electronics systems promise reduced electricity consumption, resulting in fewer harmful energy-related emissions.
More efficient power electronics would use less energy, saving American families and business owners money on their power bills.
Innovation Update: 
(As of May 2016)
Through two ARPA-E-funded projects – one through OPEN 2009 and a later project through the SWITCHES program, Soraa has built and scaled a growth chamber capable of fabricating GaN wafers at least two inches in diameter. Using its growth method, Soraa has been able to fabricate GaN wafers to produce LEDs at a higher density without a significant decrease in efficiency. The company introduced its first commercial product, MR16 LED lamps, in 2012. Soraa will continue to improve their process to make GaN crystals for power electronics. Ultimately, the team seeks to build a commercial GaN growth facility. 
Semiconductor wafer sizes must continually increase in order to drive down costs. Soraa’s innovations will help the continuous scaling of GaN wafers, which is necessary to enable higher power LEDs and power electronics that will improve U.S. energy efficiency.
During Soraa’s OPEN 2009 project, the team built a six-inch diameter ammonothermal reactor and demonstrated that it could safely grow high-quality GaN crystals at a rate of at least 10 microns per hour. Through its subsequent work under the ARPA-E SWITCHES program, Soraa built a six-inch diameter reactor that is 350x larger than early prototypes. In order to do so, the team had to overcome various technical challenges to the reactor design and process. The resulting reactor design and growth process eliminates leaking, improves temperature uniformity, optimizes internal loading of seeds and polycrystalline raw material, increases heater lifetime, and improves growth uniformity at all locations throughout the capsule. 
For a detailed assessment of the Soraa team's project and impact, please click here.

ARPA-E Program Director: 
Dr. Timothy Heidel
Project Contact: 
Dr. Mark D'Evelyn
Release Date: