Analysis of Co and Cr dopants in epitaxial films of beta-FeSi2 by ERDA, RBS, EDX and AES

Thin films of beta-FeSi2 doped with Co or Cr were grown on Si substrates by molecular beam epitaxy. The matrix components Fe and Si and the dopant wer e co-evaporated from three separately controlled sources. The dopant concen tration was measured concurrently by ERDA, RES, EDX and AES. Ion scattering spectrometry using heavy-ion beams of high energy (ERDA with 250 MeV Xe-12 9, RES with 15 MeV N-14) proved to be most powerful in providing a high mas s resolution (1 amu) and a low detection limit for Co and Cr (about 0.2 at %). Although the sensitivity of standard RES (with 1.4 MeV He-4), EDX and A ES is limited to a level of about 1 at% these methods allow to assess essen tial trends caused by variation of the deposition parameters.