Anomalous Diffusion of Mo Implanted into Aluminium

Mo ions are implanted into aluminium with a high ion flux and high dose at elevated temperatures of 300°C, 400°C and 500°C. X-ray diffraction spectra show that the Al₁₂Mo phases are formed. Rutherford backscattering spectroscopy indicates that a profile of Mo appears in Al around the depth of 550nm and with an atomic concentration of ～7%, when Mo is implanted to the dose of 3×10¹⁷/cm² with an ion flux of 45μA/cm²(400°C). If the dose increases to 1×10¹⁸cm² at the same ion flux, the penetration of Mo ions in Al can reach a depth of 2μm, which is greater than the ion project range Rp(52.5nm). The results show that anomalous diffusion takes place. Owing to the intense atom collision cascades, the diffusion coefficient increases greatly with the increase of the ion flux and dose. The Mo diffusion coefficients in Al are calculated. The Mo retained dose in Al increases obviously with the increase of the ion flux.