Energy gap tuning and optical properties of γ-Si3N4 doped with Fe, Co and Ni

The significantly decreased energy gaps, enhanced absorption coefficient, and improved electron transition of γ-Si3N4 caused by doped Ni atoms are reported. Three transition elements (Fe, Co, and Ni) are used as candidate dopants. Based on density functional theory calculations, nine doped structures are appreciated with formation and binding energies. Each dopant effect on the optical properties is explored at four concentrations. The results provide a basis for future investigations of tailoring and developing new high-performance doped γ-Si3N4.