Indium (III) sulfide has recently attracted much attention due to its potential in optical sensors as a photoconducting material and in photovoltaic applications as a wide direct bandgap material. On the other hand, optical absorption properties are key parameters in developing high photosensitivity photodetectors and high efficiency solar cells. We show that indium sulfide nanorod arrays produced by glancing angle deposition technique have superior absorption and low reflectance properties compared to conventional flat thin film counterparts. We observed an optical absorption value of approximately 96% for nanorods in contrast to 80% for conventional amorphous-to-polycrystalline thin films of indium sulfide. A photoconductivity response was also observed in the nanorod samples, whereas no measurable photoresponse was detected in conventional thin films. We give a preliminary description of the enhanced light absorption properties of the nanorods by using Shirley-George model which predicts diffusion of light by the roughness on the surface.
Vertically
aligned catalysts comprised of platinum–nickel
thin films on nickel nanorods (designated as Pt–Ni@Ni-NR) with
varying ratios of Pt to Ni in the thin film were prepared by magnetron
sputtering and evaluated for their oxygen reduction reaction (ORR)
activity. A glancing angle deposition (GLAD) technique was used to
fabricate the Ni nanorods (NRs) and a small angle deposition technique
for growth of a thin conformal coating of Pt–Ni on the Ni-NRs.
The Pt–Ni@Ni-NR structures were deposited on glassy carbon
for evaluation of their ORR activity in an aqueous acidic electrolyte
using the rotating disk electrode technique. The Pt–Ni@Ni-NR
catalysts showed superior area-specific and mass activities for ORR
compared to those of Pt–Ni alloy nanorod catalysts prepared
using the GLAD technique and compared to those of conventional large-surface
area Pt and Pt–Ni alloy nanoparticle catalysts.
In this study, a detailed experimental and theoretical investigation of optical absorption properties of indium sulfi de (In 2 S 3 ) nanostructure arrays in different shapes are presented. Zigzags, springs, screws, tilted rods, and vertical rods of In 2 S 3 are grown using a glancing angle deposition (GLAD) technique. Nanostructured coatings are of similar material volume and porosity, yet with different shapes. Total optical refl ection, transmission, and absorption profi les of In 2 S 3 nanostructures are obtained by UV-vis-NIR spectroscopy using an integrating sphere. Measurements reveal that optical absorption of semiconducting nanostructures can strongly depend on their shapes. Under normal incidence of light, 3D geometries such as springs, screws, and vertical rods can provide enhanced absorption compared to zigzags, and tilted rods.
Results of fi nite difference time domain (FDTD) simulations predict that spring, screw, and tapered-rod shapes can introduce a uniform distribution of diffracted light intensity and stronger absorption within the nanostructured layer, indicating an enhanced diffuse light scattering and light trapping.Zigzags and tilted rods show a relatively weaker absorption, similar to the experimental results. Experimental and simulation results are also compared to the predictions of effective medium theory. Current effective medium approximations are not suffi cient to explain the high optical absorption of the nanostructures.Adv. Optical Mater. 2013, 1, 158-166 159 wileyonlinelibrary.com
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