Damage recovery in ZnO by post-implantation annealing

ZnO bulk samples were implanted with 200 keV-Co ions at room temperature with two fluences, 1 × 1016 and 8 × 1016 cm−2, and then annealed in air for 30 min at different temperatures up to 900 °C. After the implantation and each annealing step, the samples were analyzed by Rutherford backscattering spectrometry (RBS) in random and channeling directions to follow the evolution of the disorder profile. The RBS spectra reveal that disorder is created during implantation in proportion to the Co fluence. The thermal treatments induce a disorder recovery, which is however, not complete after annealing at 900 °C, where about 15% of the damage remains. To study the Co profile evolution during annealing, the samples were, in addition to RBS, characterized by secondary ion mass spectrometry (SIMS). The results show that Co diffusion starts at 800 °C, but also that a very different behavior is seen for Co concentrations below and above the solubility limit.