CHEMICAL BEAM EPITAXY OF IRON DISILICIDE ON SILICON

The growth of high quality semiconducting beta-FeSi2 layers on silicon substrates is rather difficult due to a large lattice mismatch (up to similar to 5.5% on Si(111)) and a very different crystallographic structure (an orthorhombic structure on top of the diamond one). We report on a new method using the chemical beam epitaxy (CBE) technique to stabilize at first the tetragonal alpha-FeSi2 phase (lattice mismatch similar to 0.8% on Si(111)) at similar to 550 degrees C. Then a post-annealing up to similar to 650 degrees C induces a phase transition from the alpha- to beta-phase via a tremendous coalescence of numerous small metallic alpha-grains (similar to 200 Angstrom in width) into large semiconducting beta-grains (less than or equal to 1 mu m in width) of high quality, suitable for Si integrated optoelectronic technology.