Stability and electronic structure of stacking faults and polytypes in ZnSnN2, ZnGeN2, and ZnSiN2

The formation of stacking faults and polytypes in ZnSnN2, ZnGeN2, and ZnSiN2 was investigated by the first-principles density functional theory calculations. To analyze the interactions between the layers of polytypes, we constructed an anisotropic next-nearest neighbor interaction model that reproduced the DFT fitted total energies. Our calculation showed that the stacking fault energy is around 0.28 eV/nm(2), indicating that the planar defect is expected to be formed in ZnSnN2. The formation of stacking faults can be suppressed by replacing Sn with Si. Stacking faults produce a sawtooth-like potential due to polarization charge, resulting in the separation of electron and hole carriers.