Defect characterization of damaged region of carbon implanted alumina: Effect of ion fluence and annealing

Abstract

Alumina is considered as a promising host for production of embedded nanoclusters through ion implantation methods. Alumina is also being proposed to be a structural material as an isolating ceramics for thermo-nuclear fusion reactors wherein it will be exposed to high energy radiation. In addition, C-doped alumina is being proposed for medical dosimetery. In order to use alumina for all these applications, a better understanding of defects evolutions at atomic level is required. For this purpose, in the present study, α-alumina crystals have been implanted with C ions (50 keV) with total fluence of 1 × 1015, 5 × 1015, 1 × 1016 and 1 × 1017 ions/cm2 at room temperature. The ion implanted samples have been annealed at 500 °C for 2 h in ambient atmosphere. The ion implantation profile and vacancy distribution profiles have been calculated using computer code SRIM. Depth dependent defect distributions in ion implanted and annealed samples have been experimentally determined using depth dependent Doppler broadening spectroscopy. The experimental data have been analyzed using computer code VEPFIT. The S-E profiles of ion implanted samples confirm that Al vacancy and C ion-vacancy complexes are the primary defects produced due to ion implantation. At the highest implanted dose, amorphization of damaged region is observed. On thermal annealing, samples with lower fluence (1 × 1015 and 5 × 1015 ions/cm2) are recovered followed by annealing out of defects. On the other hand, samples with higher fluence (1 × 1016 and 1 × 1017 ions/cm2) indicate the formation of open volume defects such as vacancy clusters or voids which is confirmed through S-W correlation plots.