Coalescence growth of GaN crystals on point seed crystals using the Na flux method

We have recently shown that dislocation‐free GaN crystals could be grown on a “GaN point seed” by the Na‐flux method. In order to grow larger‐diameter dislocation‐free GaN crystals, we have been trying to coalesce GaN crystals grown from many isolated point seeds. In this study, we found that two GaN crystals grown from two point seeds arranged along the a ‐direction coalesced without generating dislocations at the coalescence boundary. X‐ray rocking curve measurements showed that tilting and twisting of the c‐axis between two crystals around the coalescence boundary gradually diminished as the growth proceeded. Furthermore, three GaN crystals arranged in a triangular pattern could coalesce along the a ‐direction. These results indicate that coalescence growth may become a key technique for fabricating larger‐diameter dislocation‐free GaN crystals. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)