Fcenter in CdTe

We report on the identification by electron paramagnetic resonance (EPR) of the atomistic and electronic structure of the Te vacancy (${\mathit{V}}_{\mathrm{Te}}$) in CdTe. The resolved, isotropic hyperfine interaction with the four nearest Cd neighbors, the isotropic g value of g=2.000±0.001, and the long spin-lattice relaxation time serve as a conclusive identification of the F center. From photo-EPR investigations we obtain two threshold energies for the recharging of ${\mathit{V}}_{\mathrm{Te}}$. Its electron ionization transition from the neutral to the positive charge state at 1.4 eV determines the energetic level at ${\mathit{E}}_{\mathit{V}}$+0.2 eV. It acts as a single donor in CdTe.