Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms vol:156 issue:1-4 pages:244-251
The Emission Channeling technique has been applied to probe the lattice sites of radioactive Li-8 and Cd-111m implanted in the wide band gap semiconductors ZnTe and ZnSe, and to study the annealing behaviour of radiation induced lattice damage. The probe ions were implanted at 60 keV energy into single crystal samples at the on-line isotope separator, ISOLDE, at CERN. On implantation at low temperature (less than or equal to 180 K) the Li atoms take up tetrahedral interstitial sites in both samples. A site change of the Li atoms from interstitial to substitutional takes place with increasing temperature. In ZnSe the substitutional fraction (f(s)) reaches its maximum value (55%) at 275 K and maintains this value until 510 K; in ZnTe maximum f(s) (50%) is reached at 250 K and maintained until 440 K. At higher temperatures the Li atoms diffuse to the surface in ZnTe and to extended defects within the crystal in ZnSe. Annealing studies with emission channeling measurements with Cd-111m probes show that amorphization and lattice recovery depend strongly on sample and implantation dose. (C) 1999 Elsevier Science B.V. All rights reserved.