Structure and electrical activity of rare-earth dopants in semiconductors

We review theoretical investigations into the structure and electrical activity of rare-earth dopants in group IV and III–V semiconductors. We find that in Si, rare-earth dopants are electrically active and have a high affinity for complexing with oxygen. In contrast, rare-earth dopants in GaAs and GaN are electrically inactive and require another defect to enable them to act as exciton traps. In further contrast AlN, is distinctive as it possess a deep donor level. The result of complexes of the RE with other defects is discussed along with implications for efficient room temperature luminescence.