Structure and properties of ion-beam-modified (6H) silicon carbide

The ion-beam-induced crystalline-to-amorphous phase transition in single crystal (6H) alpha-SiC has been studied as a function of irradiation temperature. The evolution of the amorphous state has been followed in situ by transmission electron microscopy in specimens irradiated with 0.8 MeV Ne+, 1.0 MeV Ar+, and 1.5 MeV Xe+ ions over the temperature range from 20 to 475 K. The threshold displacement dose for complete amorphization in alpha-SiC at 20 K is 0.30 dpa (damage energy = 15 eV atom(-1)). The dose for complete amorphization increases with temperature due to simultaneous recovery processes that can be adequately modeled in terms of a single-activated process. The critical temperature, above which amorphization does not occur, increases with particle mass and saturates at about 500 K. Single crystals of alpha-SiC with [0001] orientation have also been irradiated at 300 K with 360 keV Ar2+ ions at an incident angle of 25 degrees over fluences ranging from 1 to 8 Ar2+ ions nm(-2). The damage accumulation in these samples has been characterized ex situ by Rutherford backscattering spectrometry-channeling (RBS/C) along the [0001] direction, Raman spectroscopy, cross-sectional transmission electron microscopy (XTEM), and mechanical microprobe measurements. (C) 1998 Elsevier Science S.A. All rights reserved.