Electron Paramagnetic Resonance and Photoluminescence Studies of Point Defects in Zinc Germanium Phosphide (ZnGeP2)

Electron paramagnetic resonance (EPR) has been used to monitor native defects, both acceptors and donors, in ZnGeP2 crystals grown by the horizontal gradient freeze technique. These active centers include singly ionized zinc vacancies (Vzn-), neutral phosphorus vacancies (VP0), and neutral phosphorus antisite defects (PGe0). The concentration of Vzn− acceptors correlates with the near-infrared optical absorption present in all ZnGeP2 crystals. A photoluminescence band near 1.4 eV is shown to be polarized and is attributed to donor-acceptor-pair (DAP) recombination. Preliminary time-decay measurements support this assignment. Observation of the EPR spectrum of Mn2+ is also reported.