The role of faceting in biaxially textured thin films: Columnar morphology and abnormal tilting
| Autor: | Yicun Huang, Susan Krumdieck, Sarah L. Masters, Catherine M. Bishop |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Characteristic morphology Surface diffusion Sticking coefficient Materials science Condensed matter physics General Physics and Astronomy 02 engineering and technology 021001 nanoscience & nanotechnology Oblique angle 01 natural sciences Crystal Faceting 0103 physical sciences Thin film 0210 nano-technology Growth theory |
| Zdroj: | Journal of Applied Physics. 128:055303 |
| ISSN: | 1089-7550 0021-8979 |
| Popis: | The ground-breaking properties of biaxially textured thin films have attracted increasing attention to the characterization and growth theory of their crystal morphologies. In particular, multi-faceted columnar structures developed during oblique angle deposition (OAD) show abnormal tilt angles that have not been previously captured by existing models. Current theories for the formation of biaxially aligned columnar structures overlook the fact that the surface diffusion on individual facets can be finite. In this work, a continuum model incorporating finite adatom mobility, flux-dependent sticking coefficient, and material-specific surface energies is employed to study the growth of a well-known MgO-OAD system. Experimentally observed morphologies are reproduced by simulating the shadowing growth of an array of preferentially oriented single crystals. We show that the abnormal tilting is elusive considering only the effects of faceting and shadowing. A proposed sticking coefficient in our model, determined by the component of adatom momentum parallel to the surface, is responsible for the development of abnormal tilting. The role of faceting is demonstrated by its effect on the resulting columnar morphologies. Using the proposed model, the characteristic morphology and tilting behavior of a CaF 2-OAD system are also obtained, which agree with experiments. |
| Databáze: | OpenAIRE |
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