Inversion Domain Boundaries in Wurzite GaN

We introduce a convenient notation to distinguish $\{10\overline{1}0\}$-planar inversion domain boundary (IDB) models. Conventionally, the existing models for IDBs, Holt-IDB and IDB*, are distinguished based on the additional $1/2 \mathbf{c}$ relative shift between the domains in IDB*. We note the $1/2 \mathbf{c}$ relative shift in IDB* can be characterized as a misalignment of stacking planes on either side of the defect. Using this fact, in our notation the existing models for $\{10\overline{1}0\}$-planar IDBs are characterized by specifying the polarity and stacking plane alignments on either side of the defect plane. By considering all the possibilities for the stacking plane alignments on either side of the defect, we propose to new models for $\{10\overline{1}0\}$-planar IDBs. One of these new models, labelled IDB’, is energetically viable and its domain wall energy is lower than Holt-IDB. Even though IDB’ has a higher domain wall energy compared to IDB*, we argue that IDB’ may be formed in typical growth conditions. We present evidence from existing literature that confirms the existence of IDB’, however the defect plane has been misidentified as Holt-IDB. Additionally, when creating supercells containing domain walls, in order to calculate associated energies using plane wave density functional theory, certain domain walls disrupt the periodicity of the supercells. We propose an improved method to produce supercells containing these types of domain walls, thereby improving the estimations of these domain wall energies.