A new paramagnetic center in ZnGeP2

An unusual E.P.R. signal is observed in as grown samples of ZnGeP₂. The defect concentration is $\text{?0.5 × 10}{}^{\mathrm{?5}}\text{(}\text{2 × 10}{}^{17}\text{cm}{}^3\text{)}$. The g-values are g_ζζ = 2.04, g_νν = 2.08 and g_ξξ = 2.00. The observed splittings are attributed to hyperfine interaction with two phosphorus ions. The hyperfine tensor, A, is extraordinarily anisotropic.