Influence of stacking faults on the quality of GaN films grown on sapphire substrate using a sputtered AlN nucleation layer

Abstract This work describes the growth and characterization of GaN films on sapphire substrate by metal organic chemical vapor deposition (MOCVD) using a sputtered AlN nucleation layer. With this approach, the density of threading dislocations (TDs) in GaN is found to be dramatically reduced by 76% compared to the conventional growth method using MOCVD-grown AlN nucleation layer. Transmission electron microscope images reveal that basal-plane stacking faults are formed at different heights beyond the sputtered AlN nucleation layer, which block the extension of TDs along the growth direction, leading to a reduction in TDs density. The formation of basal-plane stacking faults can be attributed to the sputtered AlN nucleation layer and the preferred lateral growth condition of GaN. Furthermore, the surface morphology of GaN films also improved by adopting the sputtered AlN nucleation layer. This work demonstrates that a sputtered AlN nucleation layer helps to improve the quality of GaN epitaxial layer.