Optical defects in ion damaged 6H-silicon carbide

Damage production induced in 6H-SiC single crystal by ion implantation was investigated ''in situ'' by optical transmittance and reflectance measurements and ''ex-situ'' by Rutherford backscattering-channeling spectroscopy (RES). Different ions (H, He, N, Ar, Kr) were implanted in the fluence range 10(11)-10(17) ions/cm(2) at room temperature. RES data showed that the implantation induced disorder was limited to a thickness comparable with the ion range and for a critical value of fluence the crystal-amorphous transition occurred even for implantation of light ion like H and He. The energy threshold for amorphization was equal for the different ions and it has been determined that about 23 eV/atom must be deposited in elastic collisions in order to form an amorphous layer. The transmittance, measured at 633 nm, decreased continuously with ion fluence being the decrease rate higher at low fluence. The absorption coefficient of the damaged layer has been determined for the different ions: it increased of orders of magnitude with respect to the undamaged material and ii. saturated when amorphization sets in. The absorption coefficient increased with the defects density and the cross section of defects absorption resulted independent of the ion species.