Investigation of a GaN Nucleation Layer on a Patterned Sapphire Substrate

A low-temperature GaN(LT-GaN)nucleation layer is grown on a patterned sapphire substrate(PSS)using metal-organic chemical vapor deposition(MOCVD).The surface morphology of the LT-GaN is investigated and the selective nucleation phenomenon in the growth process of the LT-GaN nucleation layer is discovered.Meanwhile,effects of thickness of the LT-GaN and the annealing process on the phenomenon are also discussed.A pattern model is also proposed to analyze the possible mechanisms in atomic scale.