Defect reduction by periodic SiN_x interlayers in gallium nitride grown on Si (111)

摘要

Periodic SiN_x 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 in this paper. A reduction of the threading dislocation density to ～ 10~9 cm~(-2) 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 SiN_x interlayer characterized using cross-sectional transmission electron microscopy, we observed a different behavior induced by the SiN_x interlayers: Si-rich inverted hexagonal pyramids with their base on the (0001) plane and six sidewalk on the (1011) plane were found near the top surface of the GaN film at the location of SiN_x insertion layer characterized using electron energy loss spectroscopy. The preferential deposition of the SiN_x on the sidewalls of the pit defects leads to the subsequently selective growth of the GaN beyond the pit defects, which leads to the burying of the pits and the reduction of the pit defects within the film due to the micromasking effect of the SiN_x.