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

Implanted radioactive Tm-167/Er-167 and Yb-169/Tm-169 impurities in Si and GaN were studied with emission channeling and photoluminescence spectroscop y. 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-te trahedral sites in Si and substitutional sites in GaN after room temperatur e implantation and annealing. O-RE complexes are formed upon co-doping with O resulting in modified luminescence signals. RE impurities remain substit utional in O-doped GaN, but are displaced from tetrahedral sites in O-doped Si. We discuss the feasibility of Mossbauer studies using Eu-151, Tm-169 a nd Dy-161 to determine the RE valence state and to identify RE defect compl exes.