Energy levels and degeneracy ratios for magnesium in n-type silicon

The energy levels and degeneracy ratios of magnesium in n-type silicon have been determined by Hall effect measurements with the least square method. Magnesium ions appear to occupy two different sites and show different electrical properties. The first is amphoteric and exhibits an acceptor level at E_c ? 0.115 eV (±0.002 eV), degeneracy ratio γ_I^? = 2.5 as well as a donor level at E_c ? 0.40 eV (±0.01 eV), γ_III⁺ = 1. The second exhibits a donor level at E_c ? 0.227 eV (±0.004 eV), degeneracy ratio $\text{γ}{}_{\mathrm{II}}{}^{\mathrm{+}}\text{=}\text{1}\text{2.5}$. The physical nature of these Mg associated site is unknown.