Periodic SiNx interlayers were employed during the metal-organic chemical vapor deposition of epitaxial GaN on AlN buffer layers grown on Si (111) substrates. The growth and the evolution of defects were studied. A reduction of the threading dislocation density to ~109/cm2 was observed on the surface of GaN by counting the surface pit density from the atomic force microscopy results. Besides the observation of the continuous bending and subsequent recombination of the threading dislocations related to the periodic conduction of the SiNx interlayer characterized using cross-sectional transmission electron microscopy, a different behavior induced by the SiNx interlayers was observed: Si-rich inverted hexagonal pyramids with their base on the (00▪1) plane and six side-walls on the (10▪1) plane were found near the top surface of the GaN film at the location of SiNx insertion layer characterized using electron energy loss spectroscopy. The preferential deposition of the SiNx on the side-walls of the pit defects leads to the subsequently selective growth of the GaN beyond the pit defects, which led to burying of the pits and the reduction of the pit defects within the film due to the micro-masking effect of the SiNx.

Defect Reduction by Periodic SiNx Interlayers in Gallium Nitride Grown on Si (111). K.Y.Zang, Y.D.Wang, L.S.Wang, S.Y.Chow, S.J.Chua: Journal of Applied Physics, 2007, 101[9], 093502