EPR identification of intrinsic and transition metal-related defects in ZnGeP2 and other II-IV-V2 compounds

Diluted magnetic semiconductors (DMS) that exhibit ferromagnetism at room temperature (RTFM) are central for the development of semiconductor spintronics. According to theoretical predictions transition metal (TM)-doped AIIBIVCV2 chalcopyrite are promising compounds for such applications. In addition to other semiconductors, they also open the opportunity to combine the observed RTFM with their excellent nonlinear optical properties, resulting into a new class of device structures for nonlinear optics and spintronics applications. These ternary compound semiconductors have two metal sites A and B that can be substituted by the TMs. A site preference for TM incorporation is crucial for the possible explanation of ferromagnetism since dependent on the TM valence state holes or electrons can be released. The magnetic resonance studies of native defects and their transition energies, EPR investigations of isolated TMs on the two different cation lattice sites, on exchanged coupled pairs as well as the interaction of TMs with native defects will be critically reviewed and the experimental results obtained are compared with theoretical predictions.