Ion Implantation and Synthesis of Materials - Studium

13.2 Ballistic Mixing 183Temperature ( C)300 100 0 -100 -1501086CrSiMIonbeamsAmount of Mixing (arb units)421Mixed layerCr002 4 6 8 10(Temperature)-1(10-3K-1)Fig. 13.4. The amount of Si atoms contained in the Cr/Si mixed layer versus reciprocalirradiation temperature (from Mayer et al. 1980)atoms can be permanently displaced from their lattice sites and relocated severallattice sites away. When this occurs at the boundary separating two differentmaterials, interface mixing results. The displacement mechanism of atomicrearrangement is the fundamental principle governing ballistic mixing.13.2.1 Recoil MixingWhen an incident ion strikes a metal target atom, M, near a metal/substrateinterface, some of the incident ion’s kinetic energy is transferred to the targetatom. For high-energy collisions, the target atoms recoil far from their initiallocation. This process, which results in the transport of atoms through repeatedsingle collision events between the incident ions and target atoms, is the simplestform of ballistic mixing. It is known as recoil implantation or recoil mixing. Formixing to be effective by this process, the recoil should travel the maximum range