Open AccessDesign of hemi-urchin shaped ZnO nanostructures for broadband and wide-angle antireflection coatings
Author(s) -
Yeong Hwan Ko,
Yun Suk Huh
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.000297
Subject(s) - nanorod , anti reflective coating , materials science , nanostructure , optoelectronics , optics , fresnel equations , rigorous coupled wave analysis , substrate (aquarium) , broadband , nanotechnology , refractive index , coating , diffraction grating , grating , oceanography , physics , geology
We study theoretically and experimentally the hemi-urchin shaped zinc oxide (ZnO) nanostructures for broadband and wide-angle antireflection coatings. The antireflective characteristics of hemi-urchin shaped ZnO nanostructures, which can be formed by integrating one-dimensional (1D) nanostructures (i.e., nanorods) on the periodic 2D structural architecture, are investigated. The optimization process is performed using a rigorous coupled-wave analysis method in terms of the order of taper of Si subwavelength gratings (SWGs) as a 2D structural architecture, the geometry of Si SWGs, and the height/size of ZnO nanorods. To simply test an experimental feasibility, a hemi-urchin shaped ZnO nanostructure is fabricated by hydrothermally growing ZnO nanorods on the periodic Si SWG structure. The angle-dependent reflectance of the hemi-urchin shaped ZnO nanostructures on the Si SWG is compared with that of the vertically aligned ZnO nanorod arrays on the Si substrate. The optimized hemi-urchin shaped ZnO nanostructure can significantly improve the antireflective property by suppressing the surface reflection over a broad spectrum and a wide range of angles of light incidence, indicating a reasonable agreement with the experimental results.