Ion channeling studies of epitaxial Fe and Co silicides on Si

Abstract

High quality epitaxial Co and Fe silicides have been grown by molecular beam epitaxy on Si(111) and Si(001) substrates with film thicknesses ranging between 25 and 8400 Å. We used Rutherford backscattering spectrometry channeling techniques to measure the lattice distortion as a function of film thickness. The critical thickness hc corresponding to the film thickness at which strain relieving dislocations begin to appear was determined for CoSi2 on Si(111) and Si(001) as well as for Si on CoSi2(111). For CoSi2 on Si(001), a larger critical thickness was obtained than on Si(111), where hc is ∼45 Å. Epitaxial Si on CoSi2(111) was found to be under a compressive strain up to thicknesses of about 350 Å depending on substrate misorientation. Strain measurements were also performed on epitaxially stabilized Co and Fe monosilicides with the CsCl structure. Channeling measurements on thick epitaxial films of bcc-Fe, Fe3Si, FeSi, and Fe0.5Si were used to determine the crystalline quality. Excellent channeling minimum yields of 4.0% were found for bcc-Fe/Si(111). The results are compared with structural information obtained from x-ray diffraction and Brillouin scattering spectroscopy.