Nano-structure and optical properties (plasmonic) of graded helical square tower-like (terraced) Mn sculptured thin films
Autor: | Ferydon Babaei, Hadi Savaloni, Araz Siabi-Garjan, Mahsa Fakharpour, Frank Placido |
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Rok vydání: | 2017 |
Předmět: |
010302 applied physics
Materials science genetic structures business.industry General Physics and Astronomy 02 engineering and technology Surfaces and Interfaces General Chemistry Discrete dipole approximation 021001 nanoscience & nanotechnology Condensed Matter Physics Polarization (waves) 01 natural sciences Molecular physics Grain size Surfaces Coatings and Films Blueshift Field emission microscopy Wavelength Optics 0103 physical sciences Thin film 0210 nano-technology business Plasmon |
Zdroj: | Applied Surface Science. 393:234-255 |
ISSN: | 0169-4332 |
Popis: | Graded helical square tower-like terraced sculptured Mn thin films (GHSTTS) are produced in three stages with different number of arms using oblique angle deposition together with rotation of substrate holder about its surface normal, plus a shadowing block fixed at the centre of the substrate holder. The structural characterization of the produced samples was obtained using field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Results showed a structural gradient with distance from the edge of the shadowing block, which in turn is responsible for the decrease in the volume of void fraction and increase of grain size. Plasmon absorption peaks observed in the optical analysis of these nano-structures showed that their wavelength region and intensity depend on the polarization and the incident angle of light, as well as the distance from the edge of the shadowing block. According to our model and discrete dipole approximation (DDA) calculations, when the number of parallel nano-rods of different lengths and radii are increased the peak in the spectrum shifts to shorter wavelengths (blue shift). Also when the diameters of the nano-rods increases (a situation that occurs with increasing film thickness) the results is again a blue shift in the spectrum. The presence of defects in these sculptured structures caused by the shadowing effect is predicted by the theoretical DDA investigation of their optical spectra. Good agreement is obtained between our theoretical results and the experimental observations in this work. |
Databáze: | OpenAIRE |
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