Ammonothermal epitaxy of thick GaN film using NH4Cl mineralizer

Single-crystalline GaN films of <= 110 mu m in thickness have been fabricated on hydride vapor phase-grown (000 1) GaN substrates by employing a relatively low-pressure (<= 170MPa) ammonothermal growth method with NH4Cl as mineralizer. Metallic Ga and polycrystalline GaN has been the chosen precursor. An average growth speed on the (0001) face of the substrate of >= 5 mu m/day was observed when using metallic Ga and about 7 pm/day for GaN. The maximum growth speed of 27.5 mu m/day was achieved for the film grown at a supersaturation from a combined Ga/GaN precursor. The surface morphology is not affected by the nature of the precursor.