Characterization of MOVPE grown AlN/GaN heterointerfaces by grazing incidence X-ray reflectivity Alloy formation at heterointerfaces

摘要

AlN/GaN heterostructures were grown by MOVPE and their heterointerfaces were characterized by grazing incidence X-ray reflectivity. The results revealed that alloy formation occurs at heterointerfaces even when conventional growth sequences and conditions are used. A lower growth temperature and a higher growth rate relieve the degree of alloy formation to some extent. A high density of pits was observed by atomic force microscopy on surfaces of AlN/GaN heterostructures with a large degree of alloy formation. These pits correspond to dislocation terminations and GaN decomposition followed by the incorporation of Ga atoms into the AlN layer probably occurs. Therefore, it is concluded that GaN decomposition during AlN growth is the primary cause of alloy formation at AlN/GaN heterointerfaces grown by MOVPE.