Cluster effect on projected range of 30Â keV C60+ in silicon

Pre-amorphized silicon wafers are implanted with 30 keV C60+ and 0.5 keV C+ ions at room temperature with fluences about 2 × 1015 atoms/cm2. The depth profiles of implanted carbon are measured using high-resolution Rutherford backscattering spectroscopy. The observed average depth of C for the C60+ implantation is 6.1 nm while that for the C+ implantation is 4.0 nm, showing a large cluster effect on the projected range.