Crystallization of GaN in Its Thermal Decomposition

抄録

GaN powder, in carbon crucibles was heated at various temperatures in an induction furnace in a nitrogen atmosphere. Deposition of Ga₂O₃ was observed on a substrate that covered the crucible during heating at above 800°C. The recrystallization of GaN was detected in the deposit formed only at 850°C probably because Ga metal deposited on the substrate reacted with an active nitrogen released in the decomposition of GaN powder. GaN also recrystallized on the substrate at 1000°C in a reaction of the evaporated Ga metal with nitrogen atmosphere. Such recrystallization was also observed when GaN powder was heated to above 850°C in an evacuated sealed quartz tube. Hexagonal thin platy crystals of about 4 μm diameter were obtained. Short duration heating at temperature close to 850°C was preferable to grow crystals because its decomposition simultaneously occurred with the recrystallization. It appears that GaN crystals do not grow in the sublimation process proposed previously but rather in the recrystallization.