Energetics and electronic structure of stacking faults in AlN, GaN, and InN

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Abstract
Basal-plane stacking faults in wurtzite AlN, GaN, and InN are studied using density-functional-pseudopotential calculations. The formation energies follow the trend exhibited for the zinc-blende/wurtzite energy differences in the bulk materials, namely, lowest energy for GaN and highest for AlN. Type-I stacking faults have the lowest energy, followed by type-II stacking faults, and finally extrinsic stacking faults. We also examine a type of intrinsic stacking fault that has not, to the best of our knowledge, been previously discussed; its energy is slightly lower than the type-II faults. Investigations of the electronic structure reveal that there are no localized states in the band gap. However, stacking faults can bound a quantum-well-like region of zinc-blende material surrounded by the wurtzite host, giving rise to a luminescence line below the wurtzite band gap.