Patent ID: 8236267

Claim:
A cylindrical high-pressure vessel having a chamber and suitable to grow group III nitride crystals comprising a main body and two lids, one on each end of the main body, the main body being made of precipitation hardenable Ni—Cr based superalloy, having its longest dimension along the vertical direction, its inner diameter larger than 2 inches, its minimum outer diameter larger than 4 inches, its vertical length of the main body more than 5 times the inner diameter, and further comprising the following features: (a) the chamber of the high-pressure vessel is divided into at least three regions along the vertical direction with flow-restricting baffles comprising regions closest to the both lids and a crystallization region; (b) the crystallization region is located between the regions closest to the both lids and is configured to be maintained at a temperature greater than said regions closest to the both lids during crystal growth; (c) the regions closest to the both lids are configured to be maintained at a lower temperature than other regions during crystal growth; (d) and a nutrient region is located above the crystallization region, wherein (e) the main body is made of forged round rod or forged hollow rod of which a primary forging pressure is applied along the radial direction of an original billet; (f) the two lids on the both ends are closed with clamps; and (g) the clamps are made of forged disks of precipitation hardenable Ni—Cr based superalloy of which the primary forging pressure is applied along the longitudinal direction of an original billet from which the disk are formed.