Ion-beam induced effects in α-Al2O3 at 15 K

In order to study the primary effects of ion-beam induced damage formation in sapphire, implantation and subsequent damage analysis by Rutherford backscattering spectrometry (RBS) in channelling configuration were performed at 15 K without change of the sample temperature. We used 80 keV Na, 150 keV K and 150 keV Ar to investigate the damage accumulation with increasing ion fluence. During the RBS measurement with 1.4 MeV He ions at 15 K, defect annealing was observed. From the measured channelling spectra, defect profiles were calculated using the computer code DICADA. These profiles are narrower and distinctly lower than those calculated by SRIM2003, especially below the surface. This suggests an enhanced recombination of defects within this area. The damage concentration at the peak maximum is analysed as a function of ion fluence or rather displacements per atom. The model that was applied contains two different types of defects, namely point defects and clusters and takes into account the defect annealing under the He beam. For both defect profiles and damage accumulation, no significant influence of the implanted ion species was observed.