Further insights into the growth mechanism of the non-stoichiometric θ-Ni2Si phase

International audienceThe solid state reaction of 50 nm Ni with Si(100) substrate was investigated using in situ X-ray diffraction (XRD). The sequence is simultaneous; it begins by δ-Ni2Si phase then the metastable θ-Ni2Si phase is formed. Both phases grow simultaneously. The growth mechanism of the non-stoichiometric θ-Ni2Si phase is discussed on the basis of the evolution of its XRD peak during annealing. The results show that, during its growth, the non-stoichiometric θ-Ni2Si phase is split into two regions of different concentrations. This “original” behavior is justified by the discontinuous variation with composition of both the diffusion coefficient and the d-lattice spacing through the θ-Ni2Si phase