Site symmetry approach in the supercell model of carbon-doped ZnO bulk

Abstract

Carbon-doped zinc oxide is one of promising materials for technological applications due to its ferromagnetism observed at room temperature. When using the hybrid DFT-HF Hamiltonian based on the PBE0 exchange-correlation functional for large-scale calculations on defective ZnO:C single crystal, we have shown that application of supercell model for carbon impurity located at O site of wurtzite-structured ZnO bulk results in the dependence of calculated formation energy of the point defect (Eform) on the selected site symmetry of the substituted atom in the supercell. For a more symmetric C3v site usually used for simulation of defective ZnO structures, values of formation energy per single dopant in supercell essentially exceed those evaluated for less symmetric C1 and Cs sites. On the other hand, each of these three types of Eform does not noticeably differ depending on supercell size if it is large enough to neglect lateral interaction between adjacent dopants. Influence of site symmetry on the electronic structure of C-doped ZnO is discussed too. The suggested approach can be further applied to a wide class of defects in crystalline solids allowing the detailed analysis of electron density localization in a defective crystal and more accurate reproducing the formation energy of point defect.