Study of crystal damage by ion implantation using micro RBS/channeling

The combination of microbeam implantation and in-situ micro RBS/channeling analysis in the Rossendorf nuclear microprobe facility enables crystal damage studies with high current densities not achievable in standard ion implantation experiments. Si(1 0 0) samples were implanted with 600 keV Si+ ions and a fluence of 1 × 1016 cm−2. Using a beam spot of 200 μm × 200 μm current densities from 4 to 120 μA/cm2 were obtained. The substrate temperature was varied between RT and 265 °C. The implanted regions were subsequently analysed by micro RBS/channeling with a 3 MeV He+ beam having a spot size of 50 μm × 50 μm. Crystal damage up to amorphisation was observed in dependence on the substrate temperature. Above a critical temperature TC no amorphisation occurs. TC was determined for each series of samples implanted with the same ion current density j. It was found that the empirical Arrhenius relation j ∼ exp(−Ea/kTC), known from standard implantation experiments, is also valid at high current densities. The observed Arrhenius law can be derived from a model of epitaxial crystallisation stimulated by defect diffusion.