Interfacial sources of extended defects in nonpolar and semipolar III-Nitride semiconductors

Abstract

The principal characteristic of nonpolar and semipolar heteroepitaxial interfaces is their anisotropy that leads to distinct ways of misfit accommodation along two in-plane directions. One direction can require misfit dislocations with out-of-plane Burgers vectors that induce epilayer tilts and low-angle grain boundaries, and the other necessitates the introduction of multiple basal-plane stacking faults. The reduced bicrystalline symmetry also favours the coexistence of distinct epilayer orientation relationships. This may result in nanocrystalline interfacial zones comprising low-energy grain boundaries that act as defect sources for the matrix epilayer, generating threading dislocations and stacking faults.