INVESTIGATIONS ON THE LOCAL STRUCTURE AND THE EPR PARAMETERS FOR<font>Cu</font>²⁺-DOPED<font>GaN</font>

Abstract

The local structure and the EPR parameters (g factors and the hyperfine structure constants) for Cu 2+ in GaN are theoretically studied from the perturbation formulas of these parameters for a 3d 9 ion in trigonally distorted tetrahedra. In these formulas, the ligand orbital and spin-orbit coupling contributions are taken into account from the cluster approach, in view of the strong covalency effect of the system. Based on the studies, the impurity Cu 2+ is found not to occupy exactly the host Ga 3+ site but to suffer a slight displacement (≈ 0.004 Å ) towards the ligand triangle along C 3 axis due to charge and size mismatching substitution. The theoretical EPR parameters show good agreement with the experimental data. The validity of the impurity displacement is also discussed.