Temperature dependence of the surface morphology of sputtered YBa₂Cu₃O₇films

Abstract

A systematic study of the surface morphology of sputtered YBa2Cu3O7 films, as a function of temperature, was performed by means of atomic force microscopy. The investigated films display spiral-shaped islands with a central terrace that is typically much larger than the subsequent terraces. A careful analysis of the observed spirals shows that the change in terrace width occurs within a narrow range of angles. Possible causes for this cross-over, e.g. the role of dislocation stress or the existence of an Ehrlich–Schwoebel barrier, are discussed. Furthermore, the temperature dependences of the central terraces, as well as of the outer terraces, are found to follow an Arrhenius law. These findings are discussed within the framework of a recently developed two-component growth model, where a rate-limiting metallic species (Y, Ba or Cu) is deposited in a reactive gas (in our case O2). The model indicates that the supersaturation of the components involved is much less than assumed previously.

The Role of Surface Diffusion in the Growth Mechanism of Triosephosphate Isomerase Crystals

“…The conclusion of surface diffusion resulting from the violation of eq is not contradicted by the presence of multilayer stacks of 2D islands with a central island that is much wider than the underlying terraces (“wedding-cake”-like structures) observed on growing (011) faces (Figure a). These structures can be explained by the existence of an extra contribution – E sch to the energy barrier for admolecules incorporating into a step from the lower terrace .…”