Optically detected magnetic resonance experiments on native defects in ZnGeP2

In order to investigate the defects responsible for the sub-band-gap absorption in ZnGeP2 optically detected magnetic resonance (ODMR) using the magnetic circular dichroism of the absorption (MCDA) as detection channel was applied. This is the first ODMR study of defects in II–IV–V2 chalcopyrites. The experiments exhibit that three different native defects contribute to the absorption in the spectral range from 0.5eV to the band-gap energy of about 2.0eV. The Ge antisite defects show a dominant transition near the band edge. Zn vacancies show strong MCD above 1.6eV and below 1eV, and the P vacancies are detected over the complete spectral range. In combination with photoinduced EPR studies these results reveal the contributions of the different defects to the broad absorption band. Peculiarities in the MCD of the Zn-vacancies are explained in terms of long spin–lattice relaxation times.