Magnetooptical investigations on electron irradiated GaN

Optically Detected Magnetic Resonance (ODMR) and Level Anti-Crossing (LAC) experiments are employed to characterize the properties of two photolumines cence bands at 0.93 eV and 0.875 eV observable in electron irradiated GaN. Only one almost isotropic ODMR line and no LAC feature appear when monitori ng the 0.93 eV emission, whereas two ODMR and two LAC signals can be found connected to the 0.875 eV band from spectral dependence studies. One possib le explanation for the recombination leading to the 0.875 eV emission is a transition between excited states and ground state of a deep donor, where t he ODMR signals arise from microwave induced transitions within the manifol d of excited states. Within this manifold avoided crossings of the magnetic sublevels give rise to the observed LAC signals.