Donor centers in zinc germanium diphosphide produced by electron irradiation

The properties of defects in p‐type zinc germanium diphosphide (ZnGeP 2 ) were studied by means of electron paramagnetic resonance (EPR) and photo‐EPR. Besides the well‐known three native defects (V Zn , V P , Ge Zn ) an S = 1/2 EPR spectrum is observed in electron‐irradiated ZnGeP 2 with an isotropic g = 2.0123 and resolved hyperfine splitting from four equivalent I = 1/2 neighbors. This spectrum is caused by a new center generated by the electron‐irradiation and not by an existing center that is recharged as a result of the irradiation induced Fermi‐level shift. It is tentatively assigned to the isolated Ge vacancy. Observation of the photoinduced recharging processes demonstrates that the location of the level V Ge 3–/2– is at E opt = (0.7 ± 0.06) eV. An annealing of the electron‐irradiated samples causes a reverse shift of the Fermi level in direction to its original position and is accompanied with a reduction of an isotropic unstructured line at g = 2.003 caused by the irradiation damage.