Laser irradiation effects on high dose implanted Cu and Pb in polycrystalline aluminum

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Abstract
High dose implanted Cu and Pb profiles show considerable rearrangement after Q-switched ruby laser pulse irradiation, when observed using 1.6 MeV 4He+ Rutherford backscattering. Cu rearranged profiles may be interpreted as due to a Cu atom diffusion into a liquid Aluminum phase (under a condition of constant concentration at the side of the implanted profile toward the bulk of the sample). Such a liquid phase is predicted by the solution of heat diffusion equation, allowing for changes of state. Numerical results are in agreement with the observed threshold for the energy density of the laser pulse in order to see a redistributed profile and yield a numerical value for the diffusion coefficient of Cu in liquid Aluminum (DL ⋍ 1.7·10−3 cm2/sec). Pb profiles undergo a more complicated process, during which, in addition to Pb-atom diffusion into the bulk, Pb atoms also move to the surface of the Al sample as a consequence of a low segregation coefficient. Experimental results are also consistent with evaporation of Pb atoms (with Al) at the highest energy density of the laser pulse