Modification of c-axis sapphire implanted with high dose yttrium ions

Single crystalline samples of [0 0 0 1]alpha-Al2O3 were implanted with 171 keV yttrium ions to high doses of 1 x 10(17) and 9x10(17) ions/cm(2) at roo m temperature (RT) and then isothermally annealed at temperatures ranging f rom 500 degrees C to 1050 degrees C in air. The lattice damage in sapphire induced by ion irradiation and the thermal annealing behavior were analyzed using Rutherford Backscattering Spectrometry and Channeling (RBS-C) and X- ray diffraction (XRD). The microhardness of the implanted surface layers wa s also measured by use of a Vickers microhardness tester before and after a nnealing. For the 1x10(17) ions/cm(2) as-implanted sample an amorphous laye r with a width of about 50 nm was observed. After annealing at 900 degrees C in air for 10 h, RBS-C measurements show that the amorphous layer recryst allized epitaxially about 9.3 nn. and XRD results indicate the formation of YAl precipitates with [0 0 2] preferred orientation with respect to [0 0 0 1] of the substrate. For specimens implanted with 9x10(17) ions/cm(2). the degradation of microhardness in the near surface layer is roughly linear w ith annealing temperature, and the XRD measurements reveal the Formation of YAl3 precipitates. (C) 1999 Elsevier Science B.V. All rights reserved.