ZnO(0001) substrates were ion implanted with 100 keV of Co and 300 keV of Gd at different fluences ranging from 5× 1013 -1× 1015 / cm2. The resulting Co:ZnO and Gd:ZnO samples were analyzed with respect to their structural, magnetic, and optical properties. The effect of annealing at 350 °C on the structure and the resulting magnetic and optical properties were investigated as well. For Co:ZnO hardly any changes were observable, neither in the structural nor in the magnetic properties, even though the existence of substitutional Co2+ in the ZnO lattice could be shown by means of low temperature photoluminescence especially for Zn-annealed samples. For the much larger Gd ion the implantation leads to a changed crystal structure, which leads to a ferromagneticlike behavior for higher implantation doses, which could even be enhanced by annealing in vacuum. Ferromagnetic behavior in annealed Gd:ZnO is corroborated by ferromagnetic resonance measurements at low temperatures. The distinct behavior of Gd- and Co-implanted ZnO highlights the importance of defects in the understanding of the magnetic properties in dilute magnetic semiconductors.
ASJC Scopus subject areas
- Physics and Astronomy(all)