Interdiffusion in compositionally modulated amorphous Nb/Si multilayers

Compositionally modulated amorphous Nb/Si multilayers with a repeating length of 3.2 nm have been prepared by an ion beam sputtering technique. The interdiffusion phenomenon in a amorphous Nb/Si multilayer is investigated by using an in-situ X-ray diffraction method. The interdiffusion coefficient D-c is determined by measuring the intensity decay of the first-order modulation peak arising from the modulation as a function of annealing time. The temperature dependence of D-c in the range of 423-523 K is described by D-c = 2.2 x 10(-18) exp(-0.55 eV/k(B)T) m(2) s(-1). A defect trap-retarded diffusion mechanism is suggested to explain the small value of pre-exponential factor D-0 in the amorphous Nd/Si multilayer films obtained by this X-ray diffraction method.