Vertically aligned arrays of aluminum (Al) nanorods were fabricated by glancing angle deposition (GLAD) method. Nanorods with maximum lengths of 200 and 350 nm were grown on 100 nm flat Al thin film. Total and diffuse reflectance profiles were measured using an ultraviolet–visible–near infrared (UV-Vis-NIR) spectrophotometer utilizing an integrating sphere to study detailed optical properties of Al nanorods in comparison to conventional planar Al thin film samples. Finite-difference-time-domain (FDTD) optical modeling method was utilized to simulate the optical response of Al nanorod array and thin film structures. FDTD simulations were carried out for periodic and random arrays of Al nanorods as well as for an isolated single nanorod in order to investigate effects of geometrical structure on plasmonic and light trapping effects. UV-Vis-NIR spectrum results reveal that total reflectance is inversely proportional with nanorod length, and decreases down to as low as ∼25%–30% in the visible spectrum at wavelengths smaller than ∼750 nm, while it stays at ∼85%–90% for flat Al thin films at those wavelengths. FDTD simulation results indicate significant light absorption by GLAD Al nanorods mainly originating from enhanced light trapping and surface plasmon resonance among the nanorods.

Al-doped ZnO (AZO) nanostructure arrays with different shapes (tilted rods, vertical rods, spirals, and zigzags) were fabricated by utilizing glancing angle deposition (GLAD) technique in a DC sputter growth unit at room temperature. During GLAD, all the samples were tilted at an oblique angle of about 90°with respect to incoming flux direction. In order to vary the shapes of nanostructures, each sample was rotated at different speeds around the substrate normal axis. Rotation speed did not only affect the shape but also changed the microstructural and optical properties of GLAD AZO nanostructures. The experimental results reveal that GLAD AZO nanostructures of different shapes each have unique morphological, crystal structure, mechanical, and optical properties determined by scanning electron microscopy, X-ray diffraction, transmission, and reflectance measurements. Vertical nanorods display the largest grain size, minimum strain, lowest defect density, and highest optical transmittance compared to the other shapes. Growth dynamics of GLAD has been discussed to explain the dependence of structural and optical properties of nanostructures on the substrate rotation speed.

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