Defect physics in rare-earth doped wide band-gap materials

Rare-earth (RE) doped wide band-gap materials are of great interest for optoelectronic and spintronic applications. The determination of defect energy levels associated with RE-related defect centers has been challenging, however, both in experimental and theoretical/computational studies. Yet such knowledge is crucial to understanding luminescence or persistent luminescence in the materials. In this talk, we present a hybrid density-functional study of the interaction between RE dopants (Er, Eu, Dy, etc.) and host materials (GaN and SrAl₂O₄), including intrinsic point defects and other impurities that may be present in the host materials. In light of our results, we identify possible luminescent RE-related centers and elucidate luminescence (or persistent luminescence) mechanisms in the RE-doped materials and develop guidelines for defect engineering to design materials with improved performance.