High-pressure solution grown hexagonal GaN platelets have been used as substrates for subsequent solution growth of GaN in the < 0 0 0 1 > directions and also for hydride vapor phase epitaxial (HVPE) growth of GaN. The solution growth was stabilized due to the application of large positive temperature gradient perpendicular to the surface,of the GaN substrate. The growth by HVPE was carried out at atmospheric pressure in a horizontal quartz reactor. Relatively rapid growth rates of about 10 mum/h and about 50 mum/h have been achieved on the Ga-polar (0 0 0 1) surface of the substrates for solution growth and HVPE, respectively, which constitutes an increase in the c-direction growth rate for both methods. Both methods produced nearly dislocation-free GaN. (C) 2002 Elsevier Science B.V. All rights reserved.