Inversion domain boundaries and phase separation in p-AlGaN layers with high Al contents

Abstract

The effect of Mg incorporation and Al composition on the formation of inversion domain boundaries (IDBs) and self-assembled superlattices in Mg-doped p-AlxGa1−xN epilayers grown on undoped Al0.3Ga0.7N was investigated by transmission electron microscopy. The formation, initiating position, and shape of the faceted IDBs strongly depended on the Mg and Al contents. Horizontally well-aligned self-assembled superlattices with large composition modulation by phase separation were also observed in the Mg-doped p-AlGaN before the formation of the faceted IDBs. The periodicity of the modulation obtained from the diffused streaks is ∼40Å.