Low-pressure acidic ammonothermal growth of 2-inch-diameter nearly bowing-free bulk GaN crystals
Kouhei Kurimoto, Quanxi Bao, Yutaka Mikawa, Kohei Shima, Toru Ishiguro, Shigefusa F. Chichibu
Abstract
Abstract Seeded growth of 2-inch-diameter GaN crystals via low-pressure (∼100 MPa) acidic ammonothermal method is demonstrated. Nearly bowing- and mosaic-free GaN crystals exhibiting full-width at half-maximum values for the 0002 X-ray rocking curves below 20 arcsec were achieved on high lattice coherency c -plane SCAAT TM seeds with gross dislocation densities in the order of 10 4 cm −2 . The photoluminescence spectra of the grown crystals exhibited a predominant near-band-edge emission at 295 K, of which intensity was one order of magnitude higher than the characteristic deep-state emission bands. A nearly bowing-free 60 mm × 60 mm c -plane GaN crystal was eventually obtained.