Growth and Properties of Epitaxial Silicides on Si(III)

Abstract

The Schottky-barrier heights ϕB of epitaxial NiSi2 and CoSi2 layers on Si(111) have been measured as a function of growth conditions. For type B NiSi2 interfaces both I-V and photoelectric methods yield a high ϕB = 0.75 ± 0.03 eV for layers grown below 400°C, dropping below 0.7 eV for layers annealed above 550°C or grown by MBE above 550°C. ϕB of type A interfaces is always found to be low, i.e., ϕB = 0.62 ± 0.03 eV. Pinhole-free ultrathin (14-70 Å) CoSi2 layers could be grown for the first time by using a novel solid phase epitaxy (SPE) technique, in which Co and Si are coevaporated in their stoichiometric ratio near room temperature (R.T.). These layers become perfectly epitaxial with type B orientation upon annealing to only 250°C and remain continuous up to Ts ≈ 600°C. From photoelectric measurements CoSi2 layers grown at Ts < 350°C are found to exhibit a high ϕB = 0.75 ± 0.04 similar to B-type NiSi2.