Surface morphology control of nonpolar m‐plane AlN homoepitaxial layers by flow‐rate modulation epitaxy

Abstract

We investigate the surface morphologies of nonpolar m‐plane AlN homoepitaxial layers grown by flow‐rate modulation epitaxy (FME). As source supply sequences, we employ a continuous supply and three types of FME: group‐III‐source FME, group‐V‐source FME, and FME with groups III and V alternated. We reveal that the average V/III ratio affects the step‐flow velocity in +c‐ and a‐directions, which determines step direction. In addition, steps toward the +c‐direction tend to bunch under N‐poor conditions. This is probably due to enhanced adatom migration resulting from the FME technique. Thus, we can control the surface morphologies of m‐plane AlN homoepitaxial layers and thereby obtain a flat surface with well‐aligned steps.