Direct Measurements of Surface Strain-Mediated Lateral Interactions between Adsorbates in Colloidal Heteroepitaxy

Surface strain can alter the dynamics of adsorbates, and often, the adsorbates themselves induce and interact via their surface strain fields. In epitaxy, such strain-mediated effects get further compounded when a misfit strain exists due to lattice mismatch between the growing film and substrate. Here, we carry out particle-resolved imaging of heteroepitaxial growth of multilayer colloidal films where the particles interact via a short-range attraction. Surprisingly, although the misfit strain relaxed systematically with film thickness, the adcolloid diffusivity was nonmonotonic. We show that this nonmonotonicity stems from the competition between the spatial extent of self-induced in-layer strain and the short interaction range. Importantly, we provide direct evidence for long-ranged strain-mediated interactions between adsorbates and show that it alters the growing film's morphology.

Automated summary

Surface strain affects the dynamics of adsorbates and their interactions. In the case of epitaxy with lattice mismatch, strain-mediated effects are further compounded. In this study, we observed that the diffusivity of adsorbates in a multilayer colloidal film was nonmonotonic, even though the misfit strain relaxed with increasing film thickness. This nonmonotonic behavior can be attributed to the competition between the self-induced in-layer strain and the short interaction range. We also provided direct evidence for long-ranged strain-mediated interactions between the adsorbates, which altered the morphology of the growing film.