Domain boundaries in epitaxial wurtzite GaN

Abstract

Double positioning boundaries on {12̄10} and {11̄00} planes in wurtzite GaN epilayer grown by molecular beam epitaxy on {1̄1̄1̄}B GaP are described. Transmission electron microscopy observations demonstrate that the {12̄10} boundary extending a short distance along the c axis is characterized by a displacement of 1/2〈101̄1〉 and is associated with single growth faults in the basal plane. This boundary forms as a consequence of island coalescence. Conversely, the {11̄00} boundary originates at the epilayer/substrate interface and runs through the whole epilayer, while g.R analysis combined with high resolution electron microscopy suggests a displacement of 1/3n〈112̄0〉 (n>3) in the basal plane with an additional shift along 〈0001〉 of 1/n〈0001〉(n>3).