Formation of thin β-FeSi2 template layer for the epitaxial growth of thick film on Si(111) substrate

For the epitaxial growth of thick beta-FeSi2 films, we fabricated ultrathin beta-FeSi2 template layers (thinner than 20 nm) on Si (I 11) substrates with different methods. Surface morphology and crystallinity of the template layers were found to be dependent on the surface conditions of the substrate and the fabrication method. It was revealed that to form a smooth and continuous template, a hydrogen-terminated surface was better than that covered with a several-nanometer oxide layer. Using this surface, continuous (I I 0)/(10 1)-oriented epitaxial template was obtained by depositing 6-nm iron at 400 degreesC and subsequent in situ annealing at 600 degreesC in MBE chamber, namely, a reaction deposition epitaxy (RDE) method. Co-deposition of iron and silicon with atomic ratio of Fe/Si=1/2 allowed the forming of template layers at further low temperature. Co-deposited template layers exhibited better crystallinity and morphology than those prepared by RDE. By using the optimized template layer, we succeeded in growing high-quality thick beta-FeSi2 films on Si (I 11) substrates with sharp beta-FeSi2/Si interface. (C) 2004 Elsevier B.V. All rights reserved.