Paper TF1+SE-TuM6
Structural and Optical Properties of Metal Sculptured Thin Films on Large-Scale Prepatterned Substrates
Tuesday, November 10, 2009, 9:40 am, Room B3
| Session: |
Glancing Angle Deposition I |
| Presenter: |
E. Montgomery, University of Nebraska-Lincoln |
| Authors: |
D. Schmidt, University of Nebraska-Lincoln
T. Hofmann, University of Nebraska-Lincoln
E. Montgomery, University of Nebraska-Lincoln
B. Mbenkum, Max Planck Institute for Metals Research, Germany
M. Schubert, University of Nebraska-Lincoln
E. Schubert, University of Nebraska-Lincoln
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| Correspondent: |
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Three-dimensional (3D) metal nanostructures are of particular research interest in modern material science and engineering, due to their intriguing properties, which can differ considerably from their bulk counterparts. These size- and structure-driven properties in such 3D metal nanostructures credit themselves for potential implementation in optical, electro-mechanical, and electromagnetic systems.
We utilize glancing angle physical vapor deposition, which exploits physical shadowing and varying particle incidence azimuth for fabrication of 3D nanostructures from metals arranged in sculptured thin films (STFs). While such nanoscaffolds (typically in geometries of (slanted) columns, chevrons, screws, or spirals) are randomly distributed on untreated substrates, organized growth can be achieved on prepatterned surfaces. Self-assembled block copolymer nanolithography and nanosphere lithography are promising techniques to accomplish wafer-scale prepatterning. The desired spacing of the resulting hexagonal pattern can be tailored based on polymer chain length and nanosphere radius, respectively. Both methods are superior to conventional and electron beam lithography techniques because of small structure sizes achieved in the order of a few nanometers and large scale preparation.
This presentation elucidates our work on structure-related optical properties of different STFs from various metals grown on untreated as well as prepatterned silicon substrates by electron-beam evaporation at an oblique angle of incidence. Generalized spectroscopic ellipsometry is employed to determine the anisotropic optical constants (refractive index n and extinction coefficient k) of the thin films in the spectral range from 400 nm to 1650 nm. All investigated STFs show extreme birefringence as well as dichroism. We observe that optical properties depend rather on geometry than material [1,2].
[1] D. Schmidt, B. Booso, T. Hofmann, A. Sarangan, E. Schubert, and M. Schubert, Appl. Phys. Lett. 94, 011914 (2009).
[2] D. Schmidt, B. Booso, T. Hofmann, A. Sarangan, E. Schubert, and M. Schubert, Opt. Lett. 34, 992 (2009).