The properties of defects in p-type ZnGeP2 were studied by means of electron paramagnetic resonance and photo-electron paramagnetic resonance. Besides the well-known three native defects (VZn, VP, GeZn) an S = 1/2 electron paramagnetic resonance spectrum was observed in electron-irradiated ZnGeP2 with an isotropic g = 2.0123 and resolved hyperfine splitting from four equivalent I = 1/2 neighbors. This spectrum was caused by a new center generated by the electron-irradiation and not by an existing center that was recharged as a result of the irradiation induced Fermi-level shift. It was tentatively assigned to the isolated Ge vacancy. Observation of the photo-induced recharging processes demonstrates that the location of the level VGe3-/2- was at Eopt = 0.7eV. An annealing of the electron-irradiated samples caused a reverse shift of the Fermi level in direction to its original position and was accompanied with a reduction of an isotropic unstructured line at g = 2.003 caused by the irradiation damage.

Donor Centers in Zinc Germanium Diphosphide Produced by Electron Irradiation. W.Gehlhoff, D.Azamat, A.Hoffmann: Physica Status Solidi B, 2003, 235[1], 151-4