Density functional theory is used to investigate Eu, Er and Tm rare earth (RE) impurities in GaAs, GaN and AlN. The most stable site is when the RE is located at a group III substitutional site but in GaN and GaAs these defects do not then possess any gap levels, unlike AlN. RE-VN defects in GaN are shown to possess levels which could act as traps for excitons. The interaction of oxygen with substitutional REs is also considered.
- electrical activity
- rare-earth dopants