Flux Engineering To Control In-Plane Crystal and Morphological Orientation

• Published in: Crystal growth & design 2012-07, Vol.12 (7), p.3661-3667
• Main Authors: LaForge, Joshua M, Ingram, Grayson L, Taschuk, Michael T, Brett, Michael J
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of nanofabrication; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Porous materials; granular materials; Self-assembly; Specific materials; Structure of solids and liquids; crystallography
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg300469s

We tailored nanostructured morphology and crystal texture of iron nanocolumns by engineering the inclination and azimuthal directions of the collimated flux characteristic of glancing angle deposition (GLAD). Under continuous substrate rotation, the flux is azimuthally isotropic within one rotation. With large substrate rotation speeds, we can deposit vertical nanocolumns with a faceted, tetrahedral apex, BCC crystal structure and ⟨111⟩ fiber texture. Designing the flux to have an azimuthal 3-fold symmetry, which reflects the symmetry of the tetrahedral apex, allows us to induce both an in-plane and out-of-plane texture (biaxial texture) by evolutionary selection. In-plane crystal orientation is accompanied by a preferential azimuthal nanocolumn orientation, where the sides of tetrahedral apex are directed toward the flux direction. This work demonstrates the flux engineering technique, which can orient in-plane crystal texture and morphology of crystalline nanocolumns on amorphous substrates. This control is a useful addition to vapor–solid, physical self-assembly with the potential to improve the performance of porous thin film architectures as biaxial buffer layers, and in a variety of device applications such as photovoltaics and energy storage.