Diffusion marker experiments with rare-earth silicides and germanides: Relative mobilities of the two atom species

A marker study of the silicides (and germanides) of rare-earth elements obtained from metallic thin films on Si (and Ge) substrates indicates that Si(and Ge) atoms constitute the dominant diffusing species during the formation of these two types of compounds. Rutherford backscattering is used to distinguish between pairs of elements having different atomic weights but very similar with respect to their chemical and metallurgical behavior. An experiment conducted with the diffusion bilayer sample Ge-Tb on Si confirms the results obtained with bilayers of the type Y-Tb on Si (or Ge). Examination of the structure of the silicides which are formed provides clues about the difference in mobility between the Si and the metal atoms.