Interdiffusion and chemical ordering in composition-modulated Fe70Si30/Si amorphous thin films

The interdiffusivity and chemical ordering in compositionally modulated (Λ=20 to 40 Å) amorphous Fe70Si30/Si thin films have been measured from the decay of the satellite intensities of the (000) x-ray scattering peak during isothermal anneals in the temperature range 373–473 K. Diffusivities as low as 10−26 to 10−25 m2 s−1 have been measured. A linear dependence of D̃Λ on 1/Λ2 has been observed, providing the evidence of chemical ordering in Fe-Si alloy and leading to the determination of a critical wavelength.