Atomistic view onto solid state dewetting: Thin bismuth films with and without strain gradient

Abstract

We present a detailed study of solid state dewetting choosing epitaxial bismuth films on silicon as a model system. Exploiting both diffraction and imaging methods, we determine atomistic parameters like unit cell coverage, lattice spacings and gradients thereof through the analysis of x-ray diffraction crystal truncation rods. A different dewetting behavior of samples with and without strain gradient is revealed. Additionally, we discuss possible reasons for the impeding influence of a strain gradient, such as a reduced interface energy or increased step edge diffusion energy barrier, which we quantify by using a Johnson-Mehl-Avrami-Kolmogorov model. A model for the step edge self diffusion of Bismuth is presented.