Surface morphology of GaN nucleation layer grown by MOCVD with different carrier gas

GaN nucleation layers were grown on sapphire substrate by metal organic chemical vapor deposition (MOCVD) with different carrier gas. The morphology of nucleation layer which is crucial to GaN crystal quality was systematically studied using nitrogen and hydrogen as carrier gas. The GaN nucleation layer tends to form larger islands under H2 ambient, and forms higher density nucleation islands and thicker nucleation layer under N2 ambient.