Growth kinetics and origin of residual stress of two-phase crystalline–amorphous nanostructured films

Abstract

Composition-driven amorphous-to-crystalline transition is widely observed in sputter-deposited thin films. We have recently shown that peculiar two-phase crystalline–amorphous nanostructures can be obtained for compositions in the transition zone between single-phased amorphous and crystalline films, offering a new possibility to control surface topography and related functional properties. Here, the growth kinetics of the two-phase nanostructures formed in the transition zone is explored and related to residual stress measurements. From the analysis of top-view scanning electron microscopy images, the evolution with the film thickness of relevant parameters describing the growth process was extracted, i.e., surface coverage, volume fraction, and perimeter per unit area of the crystalline regions growing in competition with the amorphous ones. We demonstrate, supported in the aforementioned parameters, that residual stress evolution in the transition zone is governed by the nucleation, growth, and interaction of the crystalline regions during the competitive growth process. Our results shed new light on the kinetics of the crystalline–amorphous competitive growth phenomenon and demonstrate the relevance of residual stress measurements for exploring the growth mechanisms of complex film microstructures.