EPITAXIAL ORIENTATION AND MORPHOLOGY OF BETA-FESI2 ON (001) SILICON

Epitaxially aligned films of beta-FeSi2 were grown on (001) silicon by reactive deposition epitaxy (RDE), molecular-beam epitaxy (MBE), and solid-phase epitaxy (SPE). Although the matching crystallographic faces, FeSi2 (100)/Si(001), remained invariant throughout this study, two different azimuthal orientations predominanted, depending on the deposition mode and growth temperature. Films with the FeSi2[010]\\Si<110> orientation (grown by RDE at typically 500-degrees-C) were of a genuine large-area single-crystal structure; however, the surface morphology was rough due to islanding which always preceeded the formation of a continuous film. Films of the alternative azimuthal orientation FeSi2[010]\\Si<100> (which were grown by SPE at typically 250-degrees-C or by MBE at temperatures as low as 200-degrees-C on top of an SPE-grown template) have a much smoother surface morphology. However, there was some loss of purity in the epitaxial alignment at these extremely low temperatures. Excellent RHEED (reflection high-energy electron diffraction) streak patterns were observed for all the films; the technique was used for the determination of azimuthal orientation. In addition, we have shown that it is possible to determine the entire heteroepitaxial relationship using RHEED.