Bulk growth of gallium nitride: challenges and difficulties

The present status of the GaN bulk growth by High Pressure Solution (HPS) method and combination of HPS and Hydride Vapor Phase Epitaxy (HVPE) methods is reviewed. Up to now the spontaneous high pressure solution growth of GaN results in crystals having habit of hexagonal platelets of surface area of 3 cm(2) or needles with length up to I cm. Recently, the platelets and needles have been used as seeds for the HVPE growth. On the other hand, the LPE technique under pressure with pressure-grown GaN (hp-GaN), GaN/sapphire template, patterned GaN/sapphire template and free standing HVPE GaN as seeds has been examined and developed. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.