Lattice site occupation of non-soluble elements implanted in metals

Abstract

A question of fundamental interest in ion implantation metallurgy concerns the lattice site which the implanted ions will occupy at the end of their trajectories. This review describes the results of a systematic study on the basic mechanisms which determine the lattice site occupation of impurities implanted in metals. Current models on the prediction of the substitutionality are reviewed and the mechanisms of impurity-point-defect interactions on the lattice site occupation are outlined. Recent experimental results are reviewed which demonstrate that implanted ions will preferentially occupy substitutional lattice sites within the relaxation phase of the collision cascade. Their displacements from the substitutional sites are due to the interaction with point defects which leads to the formation of defect-impurity complexes. These processes occur during the cooling phase of the cascade and at temperatures at which point defects are mobile. The probability of the complex formation increases as a function of the heat of solution and the size-mismatch energy.