Studies of the g Factors and the Hyperfine Structure Constants for the Octahedral Interstitial Mn²⁺ and Cr⁺ Impurities in Silicon

The g factors and the hyperfine structure constants for the octahedral interstitial Mn²⁺ and Cr⁺ impurities in silicon are theoretically studied using the perturbation formulas of these parameters for an octahedral 3d⁵ cluster. In the calculations, both the crystal-field and charge transfer contributions are taken into account in a uniform way, and the related molecular orbital coefficients are quantitatively determined from the cluster approach. The theoretical g factors and the hyperfine structure constants are in good agreement with the experimental data. The charge transfer contribution to the g-shift (≈g-g_s, where g_s ≈ 2:0023 is the spin only value) is opposite (positive) in sign and about 51% - 116% in magnitude as compared with the crystal-field one for Mn²⁺ and Cr⁺, respectively. Nevertheless, the charge transfer contribution to the hyperfine structure constant has the same sign and about 12% - 19% that of the crystal-field one. Importance of the charge transfer contribution shows the order Cr⁺ < Mn²⁺ due to increase of the impurity valence state in the same host, especially for the g factor.