The dependency of LPE growth rate and dislocation density on supersaturation in the growth of GaN single crystals in the Na flux was investigated. When the growth rate was low during the growth of GaN at a small value of supersaturation, the dislocation density was much lower compared with that of a substrate grown by the Metal Organic Chemical Vapor Deposition method (MOCVD). In contrast, when the growth rate of GaN was high at a large value of supersaturation, the crystal was hopper including a large number of dislocations. The relationship between the growth conditions and the crystal color in GaN single crystals grown in Na flux was also investigated. When at 800 degreesC the nitrogen concentration in Na-Ga melt was low, the grown crystals were always tinted black. When the nitrogen concentration at 850 degreesC was high, transparent crystals could be grown. (C) 2004 Elsevier B.V. All rights reserved.