Two-step growth of high-quality GaN by hydride vapor-phase epitaxy

The use of a low-temperature layer of GaN formed by hydride vapor-phase epi taxy (HVPE) as a template to grow high-quality HVPE films is demonstrated. Using layers formed by reacting GaCl and NH3 at 550 degrees C and annealed at a growth temperature of 1050 degrees C, thick films of GaN can be grown by HVPE with fewer than 10(8) dislocations per cm(2). Dislocation densities measured by high-resolution x-ray diffraction, atomic-force microscopy ste p termination density and plan-view transmission electron miscroscopy revea l that similar to 23 mu m films have dislocation densities of similar to 6x 10(7) cm(-2). Obtaining high-quality single-crystal character films was fou nd to be dependent on several factors, most importantly, the rate of temper ature increase to growth temperature and the layer thickness. (C) 2000 Amer ican Institute of Physics. [S0003-6951(00)03638-X].