Kh. Chae et al., ATOMIC TRANSPORT IN COLLISIONAL ATOMIC MIXING IN BILAYER STRUCTURE, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 88(4), 1994, pp. 387-393
A dynamic Monte Carlo simulation (MCS) program, containing not only co
llisional mixing but also sputtering effects, has been used to elucida
te the dynamic mixing processes and the atomic transport of constituen
ts in Al-Pd bilayer systems. MCS results reveal that the preferential
inward displacement of the top layer element dominates, and that there
is an enhancement of the inward displacement when the heavier element
is in the top layer. The inward displacement is controlled by both of
an anisotropic and isotropic atomic transport. The anisotropic term i
s caused by the primary recoil of atoms, which has a characteristic of
phi (ion dose) dependence, and the isotropic term is associated with
the random cascade motion, which has a square-root phi dependence. How
ever the outward displacement is governed by only the isotropic motion
, thus the inward displacement always dominates over the outward motio
n, which leads to a preferential displacement of top layer element to
the bottom layer.