Development of GaN wafers via the ammonothermal method

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.