Implantation site of rare earths in single-crystalline ZnO

The lattice location of rare earth $^{167m}$Er in single-crystalline hexagonal ZnO was studied by means of the emission channeling technique. Following 60-keV room-temperature implantation of the precursor isotope $^{167}$Tm at doses of 1.3-2.8 $\times10^{13}$ cm$^{-2}$ and annealing up to 900°C, the angular distribution of conversion electrons emitted by the radioactive isotope $^{167m}$Er was measured by a position-sensitive electron detector. The conversion electron emission patterns from $^{167m}$Er around the [0001], [1102], [1101] and [2113] directions give direct evidence that the large majority of Er atoms (75-90%) occupies substitutional Zn sites.