GROWTH OF BETA-FESI2 ON SI(111) BY CHEMICAL BEAM EPITAXY

The growth of high quality semiconducting beta-FeSi2 layers on silicon substrates is rather difficult due to a large lattice mismatch [up to approximately 5.5% on Si(111)] and very different crystallographic structure (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 approximately 0.8% on Si(111)) at approximately 550-degrees-C. Then a post-annealing up to approximately 650-degrees-C induces a phase transition from the alpha to beta phase via a tremendous coalescence of numerous small metallic alpha grains (approximately 200 angstrom width) into large semiconducting beta-grains (less-than-or-equal-to 1 mum width) of high quality, suitable for Si integrated optoelectronic technology.