Scalable technology for growth of high quality single crystal gallium nitride

This Small Business Technology Transfer Phase I project will investigate the feasibility of growth of high quality, low cost bulk gallium nitride substrates by the high pressure ammonothermal method.  The proposed approach utilizes a novel apparatus which is scalable to process volumes of hundreds of liters at modest cost.  The novel apparatus will be capable of accessing process pressures above 0.6 GPa (~6,000 atm or ~90,000 psi) and temperatures above 650 °C, conditions where growth rates of high quality single crystal gallium nitride above 15 microns per hour have been demonstrated using a non-scalable apparatus.  The key deliverables for the Phase I project include:  (1) Demonstrate capability of a novel high-pressure apparatus to contain ammonia pressures and temperatures greater than 0.6 GPa and 650 °C, respectively; and (2) Demonstrate growth of GaN crystals with a crystalline quality at least competitive with HVPE GaN, with a path to achievement of world-class crystal quality. BENEFIT: If successful, the proposed work will enable a number of device applications of interest to the Air Force and will also have a large commercial impact.  Bulk gallium nitride substrates, currently in use for laser diodes only and grown by a vapor-phase technique, are projected to grow from a market size of $144M in 2008 to $405M in 2010.  The proposed approach should enable a significantly lower substrate cost and enable key technologies of interest for the Air Force and DoD, including high performance detectors and emitters and high-performance high-frequency GaN-based electronics.  A low cost native GaN substrate would also transform the substantially larger commercial market for light-emitting diodes (LEDs).  Bulk GaN substrates are expected to enable further efficiency improvements and cost reductions in GaN-based LEDs, addressing a $56B/yr long-term market opportunity and enabling a large reduction in the ~700TWh of electrical power (30% of the total electricity) consumed  in the US per year.  In the commercial arena, but of significant impact on DoD technologies, high quality, low cost bulk GaN substrates will enable new markets, such as GaN-based solar blind photodetectors, RF and power-switching transistors, and perhaps even concentrator-type solar cells, that up to now have made very little progress because of the relatively poor material quality and high cost of current bulk GaN substrates.  Finally, the proposed apparatus design, representing perhaps the largest advance in large-volume high pressure high temperature processing capability in 40 years, will be applicable to a range of other processes, including hydrothermal crystal growth.)