Lattice location and stability of implanted Cu in ZnO

Abstract

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 $2.3\ifmmode\times\else\texttimes\fi{}{10}^{13}{\mathrm{cm}}^{\ensuremath{-}2},$ the angular distribution of ${\ensuremath{\beta}}^{\ensuremath{-}}$ particles emitted by the radioactive isotope ${}^{67}\mathrm{Cu}$ was measured by a position-sensitive detector. The ${\ensuremath{\beta}}^{\ensuremath{-}}$ 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 \AA{}. However, following annealing at $600\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ and above Cu was found to be located on sites that are characterized by large rms displacements (0.3--0.5 \AA{}) from Zn sites.