Transmission electron microscopy study of an AlN nucleation layer for the growth of GaN on a 7-degree off-oriented (001) Si substrate by metalorganic vapor phase epitaxy

摘要

We have investigated the morphology of the high-temperature-grown A1N nucleation layer and its role in the early stage of GaN growth, by means of transmission electron microscopy. The nitride was selectively grown on a 7-degree off-oriented (001) patterned Si substrate by metalorganic vapor phase epitaxy. A1N was deposited on the inclined unmasked (111) facet in the form of islands. The size of the islands varied along the slope, which is attributable to the diffusion of the growth species in the vapor phase. The GaN nucleation occurred at the region where rounded A1N islands formed densely. The threading dislocations were observed to generate in the GaN nucleated region.