Defect annealing in ion implanted silicon carbide

Abstract

The recovery of lattice damage in ion implanted 6H-SiC single crystals by thermal annealing has been investigated in the temperature range 200–1000 °C by Rutherford backscattering spectrometry-channeling and by optical measurements in the UV-visible wavelength. The damage was produced by implantation at room temperature of 60 keV N+ at fluences between 1014 and 5 × 1015 ions/cm2. At low fluences a partially damaged layer with defects distributed over a depth comparable to the projected ion range was obtained. At higher fluences a continuous amorphous layer was formed. The defect annealing behavior depended on the initial damage morphology: an almost total defect recovery occurred in partially damaged layers with kinetics depending on the initial damage degree. If the defect concentration is smaller than 20 at.% the annealing rate is independent of temperature. Amorphous layers were stable in the investigated temperature range and no epitaxial regrowth occurred. After annealing, a strong change in the optical properties of the amorphous phase was observed indicating a recovery of the electronic properties of the material, suggesting the existence of several amorphous states and the relaxation of the amorphous that evolves toward thermodynamic states characterized by lower free energy values.