Emission channeling studies of defect annealing in the wide band gap semiconductors ZnTe and ZnSe

The Emission Channeling technique has been applied to probe the lattice sit es of radioactive Li-8 and Cd-111m implanted in the wide band gap semicondu ctors ZnTe and ZnSe, and to study the annealing behaviour of radiation indu ced lattice damage. The probe ions were implanted at 60 keV energy into sin gle crystal samples at the on-line isotope separator, ISOLDE, at CERN. On i mplantation at low temperature (less than or equal to 180 K) the Li atoms t ake up tetrahedral interstitial sites in both samples. A site change of the Li atoms from interstitial to substitutional takes place with increasing t emperature. 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 temper atures the Li atoms diffuse to the surface in ZnTe and to extended defects within the crystal in ZnSe. Annealing studies with emission channeling meas urements with Cd-111m probes show that amorphization and lattice recovery d epend strongly on sample and implantation dose. (C) 1999 Elsevier Science B .V. All rights reserved.