Ion Beam Mixing - Mechanism

Mechanism

The unique effects that stem from ion beam mixing are primarily a result of ballistic effects; that is, impinging ions have high kinetic energies that are transferred to target atoms on collision. Ion energies can be seen on the order of 1 keV to 200 keV. When accelerated, such ion energies are sufficiently high to break intra- and especially inter-molecular bonds, and initiate relocations within an atomic lattice. The sequence of collisions is known as a collision cascade. During this ballistic process, energies of impinging ions displace atoms and electrons of the target material several lattice sites away, resulting in relocations there and interface mixing at the boundary layer. (Note that energies must be sufficiently high in order for the lattice rearrangements to be permanent rather than manifesting as mere vibrational responses to the impinging radiation, i.e. the kinetic energies must be above the threshold displacement energy of the material.) If energies are kept sufficiently high in these nuclear collisions, then, compared to traditional high-dose implantation processes, ballistic ion implantation produces higher intrafilm alloy concentrations at lower doses of irradiation compared to conventional implantation processes.