| AVS 55th International Symposium & Exhibition | |
| Advanced Surface Engineering | Thursday Sessions |
| Session SE+TF+NC-ThA |
| Session: | Glancing Angle Deposition (GLAD) II |
| Presenter: | E.B. Schubert, University of Nebraska-Lincoln |
| Authors: | E.B. Schubert, University of Nebraska-Lincoln T. Hofmann, University of Nebraska-Lincoln D. Schmidt, University of Nebraska-Lincoln M.M. Schubert, University of Nebraska-Lincoln |
| Correspondent: | Click to Email |
Three-dimensional (3D) structure design of chiral materials on the nanoscale is a current demand in modern material science and engineering and various intriguing applications are foreseen for example in the fields of optics, electromechanics or electromagnetic. Glancing angle deposition is a method which allows for “bottom-up” fabrication of 3D shaped and tailored chiral nanostructures arranged in sculptured thin films (STF). We will present an investigation of the growth of STF’s from aluminum on highly p-type doped silicon substrates by using either ion beam sputtering or electron beam evaporation. Various growth schemes have been used to obtain films with different nanostructure shapes such as posts, plates, screws or spirals. The films have been characterized regarding their optical and electrical properties by means of 4x4 Mueller-Matrix ellipsometry, IR spectroscopic ellipsometry and electrical measurements. Whereas Mueller-Matrix Ellipsometry reveals an optical response which can be related to the symmetry of the three-dimensional nanostructures,1 the IR data give hint to electron or lattice absorptions. We found that the IR optical response depends on the shape of the nanostructures. STF’s from aluminum plates for example show a strongly metallic behavior, whereas films containing Al spirals show multiple resonances, with a periodic spectral distance of 7.2 THz between neighboring absorption features. The IR optical data for the Al nanocoils are discussed in terms of coupled inductance and capacitance pairs, where the inductance is formed from the coil itself and the depletion layer capacitance is created on the footprint of the metallic Al coil with the highly p-type doped Si substrate. A Drude-like background term, which accounts for free carriers in the aluminum nanospirals was also used during sample regression. It is found, that resistivity and free mean path of the electron depends of the shape of the Aluminum nanostructures as well. This behavior is verified by electrical measurements under dc conditions.
1 D. Schmidt, E. Schubert, and M. Schubert, phys. stat. sol. (a) 205, 748 (2008).