Lattice location and stability of implanted Cu in ZnO

The lattice location of copper in single-crystalline zinc oxide was studied by means of the emission channeling technique. Following 60-keV room-temperature implantation at a fluence of 2.3 x 10(13) cm(-2), the angular distribution of beta(-) particles emitted by the radioactive isotope Cu-67 was measured by a position-sensitive detector. The beta(-) emission patterns give direct evidence that in the as-implanted state a large fraction of Cu atoms (60%-70%) occupy almost ideal substitutional Zn sites with root-mean-square (rms) displacements of 0.16-0.17 Angstrom. However, following annealing at 600 degreesC and above Cu was found to be located on sites that are characterized by large rms displacements (0.3-0.5 Angstrom) from Zn sites.