Inversion domain boundaries in ZnO

Electronic structure and thermodynamics revealed by DFT calculations

2021/02/04 by J. Rohrer

We systematically investigated the atomic structure and chemical composition of ZnO bicrystal samples containing {0001} inversion domain boundaries (IDB) using density functional theory calculations. We find that thermodynamically favored IDBs are characterized by fully (4-fold) coordinated atoms and possess relatively low excess energies that range from 45 to 95meV/Å2, depending on the termination (Zn/Zn or O/O) and the exchange-correlation functional. The electronic properties of the GB deviate only weakly from those of the bulk and are rather insensitive towards compressive and tensile strains. Our results thus indicate that experimentally observed piezotronic properties of bicrystals are not an intrinsic property of the pristine GB itself, but originate, for example, from externally supplied trapped charges, defects, impurities, or dopants. Low-energy structure models identified here may also be transferable to other wz- or zb-type IDBs (e.g., GaN, AlN, SiC, etc.).