Ion beam mixing is the atomic intermixing and alloying that can occur at the interface separating two different materials during ion irradiation. It is applied as a process for adhering two multilayers, especially a substrate and deposited surface layer. The process involves bombarding layered samples with doses of ion radiation in order to promote mixing at the interface, and generally serves as a means of preparing electrical junctions, especially between non-equilibrium or metastable alloys and intermetallic compounds. Ion implantation equipment can be used to achieve ion beam mixing. 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. Analysis The degree of mixing of a film scales with the ion mass, with the intensity of any given incident ion beam, and with the duration of the impingement of the ion beam on a target. The amount of mixing is proportional to the square roots of time, mass and ion dose. At temperatures below 100 °C for most implanted materials, ion beam mixing is essentially independent of temperature but, as temperature increases beyond that point, mixing rises exponentially with temperature. This temperature-dependence is a manifestation of incident ion beams effectively imparting the target species-dependent activation energy to the barrier layer. Ballistic ion beam mixing can be classified into two basic subtypes, recoil mixing and cascade mixing, which take place simultaneously as a result of ion