Interdiffusion in Mo/Ge Multilayer Thin Films

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Abstract
Multilayered Mo/Ge thin films have been prepared by dual rf-sputtering technique, and the interdiffusion and structural change on annealing have been investigated by X-ray diffraction measurements. X-ray diffractometry shows that for the modulation wavelength λ shorter than 5 nm both Mo and Ge sublayers are amorphous, while for λ longer than 5 nm, crystalline bcc structure appears in Mo sublayers. The interdiffusivities have been determined from the decay rate of satellite peak intensity around (000). The temperature dependence of the effective interdiffusivities in amorphous Mo/Ge multilayer films with λ=3.4–4.2 nm is expressed as \ ildeDλ=1.3×10−16exp[−(115±7)kJ mol−1⁄RT]m2s−1 over the temperature range from 665 to 724 K. On initial annealing, the satellite peak intensity decreases drastically and the modulation wavelength decreases by 1–2%, which are interpreted to be due to structural relaxation and interdiffusion. The thermodynamic behaviour of the amorphous Mo–Ge system is discussed on the basis of the dependence of the effective interdiffusivity on λ.