Investigations of the EPR parameters and substitutional sites of Ni3+ ions in CuGaS2 and AgGaS2 ternary semiconductors

The electronic paramagnetic resonance (EPR) parameters (g factors g//, g⊥ and zero-field splitting D) of Ni3+ ions at both M+ (M = Cu, Ag) and Ga3+ sites in MGaS2 ternary semiconductors are calculated from the high-order perturbation formulas based on the two spin-orbit (SO) coupling parameter model for 3d7 ions in tetragonal symmetry. The calculated results suggest that Ni3+ ions replace the monovalent M+ ions in MGaS2 crystals. This point is contrary to the previous assumption that Ni3+ ions substitute for the isovalent Ga3+ ions to attain the charge neutrality. The reasonableness of the suggestion is discussed.