Exploring Pd–Si(001) and Pd–Si(111) thin-film reactions by simultaneous synchrotron X-ray diffraction and substrate curvature measurements

Abstract

Palladium–silicon (Pd–Si) is a model system for investigating stress development during solid state reaction because of the formation of one single phase (hexagonal Pd2Si). In this work we have measured simultaneously the curvature of the substrate and the diffracted signal from the films during reactive diffusion of a thin Pd (25nm) film with a Si(001) substrate. Only the diffracted signal was measured during the solid state reaction of Pd(25nm) with Si(111). The combined experiment allows monitoring in situ stress and strain during the growth of Pd2Si. The combination method also permits the determination of the elastic constants and thermal expansion coefficient of Pd2Si assuming an equibiaxial stress and isotropical physical properties in Pd2 Si.