Combination of emission channeling, photoluminescence and Mössbauer spectroscopy to identify rare earth defect complexes in semiconductors

Implanted radioactive 167Tm / 167Er and 169Yb / 169Tm impurities in Si and GaN were studied with emission channeling and photoluminescence spectroscopy. The effect of co-doping with oxygen on the rare earth (RE) lattice sites and their luminescence behavior was investigated. Tm and Yb occupy near-tetrahedral sites in Si and substitutional sites in GaN after room temperature implantation and annealing. O-RE complexes are formed upon co-doping with O resulting in modified luminescence signals. RE impurities remain substitutional in O-doped GaN, but are displaced from tetrahedral sites in O-doped Si. We discuss the feasibility of Mossbauer studies using 151Eu, 169Tm and 161Dy to determine the RE valence state and to identify RE defect complexes.