Lattice location and annealing behaviour of Pt and W implanted sapphire

Sapphire (alpha-Al2O3) single crystals were implanted with different doses of Pt and W ions in the range of 1x10(14) at/cm(2) to 5x10(16) at/cm(2) at room temperature. Detailed angular scans through the main axial directions show that up to 10(15) atl/cm(2) fluences about 80% of the W and Pt ions ar e incorporated into substitutional or near substitutional lattice sites. Be low the amorphization threshold implantation damage show a double peak stru cture which anneals out partially at low temperature (800 degrees C). Amorp hization of the implanted region starts for doses of the order of 1x10(16) at/cm(2). The amorphous layer regrowths epitaxially in vacuum at 1100 degre es C, with a velocity of 3 Angstrom/min and stops when the crystalline/ amo rphous interface reaches the region of maximum Pt concentration. When the a nnealing is done at ambient atmosphere the damage recovers completely at 11 00 degrees C even for doses of the order of 5x10(16) Pt+/cm(2) leading to t he formation of Pt precipitates. (C) 1999 Elsevier Science B.V. All rights reserved.