A mechanism was discovered which could significantly reduce the dislocation

density during the growth of GaN single crystals using the Na flux method. The

significant reduction in dislocation density occurred in the later stage of LPE

growth, rather than solely at the seed/LPE interface for which there was already

reported evidence which indicated the presence of bundling dislocations. The two step dislocation reduction was the key to achieving extremely low dislocation

densities using this method. A 5cm GaN crystal was grown, having a thickness of

2mm, in order to confirm that the dislocation density decreased as the growth

thickness increased. As a result, three-fourths of the surface area exhibited a

dislocation density of the order of 102/cm2, and the full width at half-maximum of

the X-ray rocking curve measurement of the (00•2) face was 28arcsec.

Growth of GaN Single Crystals with Extremely Low Dislocation Density by Two-

Step Dislocation Reduction. F.Kawamura, M.Tanpo, N.Miyoshi, M.Imade,

M.Yoshimura, Y.Mori, Y.Kitaoka, T.Sasaki: Journal of Crystal Growth, 2009,

311[10], 3019-24