Flat Surfaces and Interfaces in AlN/GaN Heterostructures and Superlattices Grown by Flow-Rate Modulation Epitaxy

AlN and AlGaN with high Al composition were grown by flow-rate modulation epitaxy (FME); a growth method in which group-III sources and group-V sources are supplied alternately. The AlN growth efficiency in FME was three times higher than those by simultaneous-supply. Vapor-Solid relation was almost linear in AlGaN grown by FME with N 2 carrier gas. In contrast to rough surfaces of AlN/GaN heterostructures grown by simultaneous-supply, the surfaces by FME were flat. Intensities of X-ray diffraction satellite peaks indicate that AlN/GaN superlattices by FME (FME-SLs) have more abrupt and flat interfaces than those grown by simultaneous-supply. The threading dislocations were effectively reduced by about half on FME-SLs. These results indicate FME is an effective growth method for the fabrication of high quality AlN/GaN heterostructures and SLs with flat interfaces.