2019 AIChE Annual Meeting

(409f) Pattern Formation on Surfaces of Strained Thin Films

Author

Maroudas, D. - Presenter, University of Massachusetts
Crystalline material nanostructures, such as quantum dots and nanorings, enable numerous applications in electronic and optoelectronic device technologies and data storage systems. The fabrication of such nanostructures typically involves the heteroepitaxial growth of thin films on substrates, where the lattice mismatch between the film and substrate materials induces a biaxial strain in the deposited film. Growing ordered arrays of such nanostructures on the strained epitaxial film surfaces has been a major challenge in this field, which has been addressed by developing growth strategies on patterned substrates.

Here, we demonstrate how ordered arrangements of complex patterns of such nanostructures can be formed by exploiting stress-induced surface morphological instabilities. We develop an atomistically-informed 3D continuum-scale model for the epitaxial film surface morphological evolution and validate it by comparisons of its predictions with experimental observations. We explore a broad range of parameter space, including geometrical parameters of pits for pit-patterned substrates, based on self-consistent dynamical simulations according to the model. The formed nanostructures include quantum dots, ordered quantum dot arrays, concentric nanorings, as well as concentric nanorings surrounding a central quantum dot. The nanostructure shapes and dimensions can be controlled precisely by properly tuning processing and geometrical parameters. The formation of the nanostructure patterns is explained by linear and nonlinear stability analyses.