Energetic and Electronic Properties of (0001) Inversion Domain Boundaries in ZnO

In this work, the eight possible configurations of (0001) inversion domain boundaries (IDBs) in wurtzite ZnO have been investigated systematically by first-principle calculations based on density-functional theory (DFT). The energetic stability revealed that H4 are the most stable among the Head-to-Head type (H) IDBs, whereas for the Tail-to-Tail type (T) IDBs, T1 and T2 IDBs have lower formation energies. Their electronic properties were investigated using the electron localization function (ELF) and the projected density of states (PDOS). The results revealed that all the boundaries present a metallic character with the hybridization bands crossing the Fermi level; they are mainly dominated by Zn:3d and O:2p states in H IDBs and Zn:4s states in T IDBs, respectively. In particular, owing to the polarization discontinuity, electron accumulation occurs at all the T IDB regions with the conduction band minimum (CBM) shifting down below the Fermi level.