Chemical effects on the amorphization of sapphire

Abstract

α-Al 2O 3 single crystals were implanted with similar doses of Pt and Hg ions at room temperature. Although the masses of the implanted species are very close, the observed defect production and annealing behaviour are quite different. In the case of Hg, a fluence of 1 × 10 15 at/cm 2 fully amorphizes the implanted region and the epitaxial regrowth occurs at low temperature (800°C) with a velocity higher than 52 Å/min. In the case of Pt the same fluence only produces a buried damage layer near the end of the range. The amorphous state is reached after the implantation of 1 × 10 16 at/cm 2 and the epitaxial regrowth occurs at high temperatures with a velocity of 3 Å/min at 1100°C. After implantation 70% of the Pt ions are in substitutional lattice sites while only 30% of the Hg occupy regular sites in a displaced octahedral position of the lattice. Hyperfine interaction measurements indicate that Hg can be associated with oxygen forming Hg–O complexes.