Ammonothermal Growth of Bulk GaN for Extended Time
|Tadao Hashimoto 1,2, Feng Wu 1,2, Makoto Saito 2,3, Kenji Fujito 3, James S. Speck 1,2, Shuji Nakamura 1,2|
1. University of California, College of Engineering, -, Santa Barbara, CA 93106-5130, United States
Recently, growth of bulk GaN crystals has been intensively researched because GaN wafers sliced from bulk crystals will solve all fundamental growth problems arising from heteroepitaxy. However, the extremely high price of state-of-the-art GaN wafers does not meet the cost requirement of LEDs for solid-state lighting. Among several bulk growth methods, the ammonothermal growth, which is the solvothermal growth using supercritical ammonia, has a high potential of realizing low-cost, high-quality GaN substrates due to its excellent scalability. In the early stage of our research, we demonstrated single-phase synthesis of wurtzite GaN powders with basic mineralizers and retrograde solubility of GaN in supercritical ammonobasic solutions. Through these experiments, we have achieved uniform growth of GaN films on an over-1-inch oval shaped seed crystal through fluid transport of Ga nutrient. However, it turned out that Ga nutrient was transformed to GaN in the nutrient crucible resulting in abrupt drop of the growth rate in about a day.
Presentation: Oral at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Tadao Hashimoto
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth
Submitted: 2007-01-20 00:17 Revised: 2009-06-07 00:44