Flow-rate modulation epitaxy of nonpolar m-plane AlN homoepitaxial layers grown on AlN bulk substrates

摘要

We investigated the surface morphologies of nonpolar m-plane AlN homoepitaxial layers grown by the flow-rate modulation epitaxy (FME) method. As source supply sequences, we adopted conventional metal-organic chemical vapor deposition (MOCVD) and three types of FME: group-III-source FME, group-V-source FME, and FME with groups III and V alternated. We found that each type of FME could improve the surface flatness of m-plane AlN compared to the conventional MOCVD. This suggests that FME can enhance adatom migration on the surface. On the other hand, the degree of step bunching and straightness of step edges depended on the type of FME. Thus, the morphological changes of the m-plane AlN depend on the source supply sequences.