Development of GaN wafers via the ammonothermal method

Autor: Edward Letts, Keith Male, Daryl Key, Mathew Michaels, Sierra Hoff, Tadao Hashimoto
Rok vydání: 2014
Předmět:
Zdroj: Journal of Crystal Growth. 403:3-6
ISSN: 0022-0248
Popis: This paper reviews the current progress of ammonothermal growth at SixPoint Materials and discusses some of the remaining challenges to commercialize the technology. The mass production of the ammonothermal grown wafers of GaN for high power devices has substantial commercial potential but is currently limited by two problems: impurities which lead to semitransparent coloration and stress in the crystals which leads to cracking. To improve the coloration, it is important to understand and reduce the impurities in the crystal. Oxygen impurities were found to be the primary source of coloration. By reducing the oxygen impurities the absorption coefficient at 450 nm was improved to 3.9 cm1 yielding semitransparent crystals. The second and more serious issue is a cracking that occurs when thick boules are produced. Currently we routinely produce ammonothermal growth over a millimeter in thickness without any cracking. However, as the thickness increases cracks develop. From a production viewpoint, the production of thick crystals is beneficial since it allows a single wafer to be processed into many. By improving a variety of parameters, the crack density was reduced and the maximum crack-free growth increased from 1 mm to 2.6 mm.
8th International Workshop on Bulk Nitrides Semiconductors (IWBNS VIII), Sept. 30-Oct. 5, 2013, Seeon, Germany
Databáze: OpenAIRE
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