Research

Crystal Growth - Selective Area Nanopillars

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The above images are contour maps representing the binding energy of adatoms to the side (110) surface and top (111) surface of a nanopillar. On the side (110) surface, there is a diffusion channel that leads adatoms up the side of the nanopillar to the tip. The top facet has larger (more negative) binding energy and deep adsorption sites where adatoms stick and incorporate into the crystal. These potential energy surface maps were generated with energy values computed with the DFT code FHI-Aims.

Predicting the growth of nanopillars requires a detailed understanding of the atom-by-atom process of self-assembly that occurs at the nanoscale. Because nanopillars are grown in a chemically hostile environment on a platter spinning at 500RPM that is heated 700°C, the traditional tools of nanoscale characterization such as electron microscopy, atomic force microscopy, and scanning tunneling microscopy are not possible. Our understanding instead comes from first-principles quantum mechanical simulations of the crystal surfaces and observations of the nanopillar properties after growth.