Fabrication and Characterization of Si Nanorod Arrays as Subwavelength Self-cleaning Antireflection Coatings
Date Issued
2009
Date
2009
Author(s)
Lin, Yi-Jui
Abstract
The antireflection (AR) coatings are utilized to suppress undesired reflection between different optical media for various optical applications. For example, Multilayered coatings are widely used on the surface of optical and optoelectronic devices. However, it is suffered from the problems, such as poor adhesion, thermal instability, and lattice mismatch. An alternative to multilayered coatings is to pattern the surface with a periodically structured array with the periodicity smaller than the wavelength of the incident light. Compared with multilayered AR coatings, subwavelength structure (SWS) surfaces show several advantages over the conventional dielectric AR coating, including broad spectral and angular response, hydrophobicity, and durable, because the AR structures are directly etched in the surface and there are no other materials involved. So far SWSs has been fabricated on silicon have been fabricated by various methods. Moreover, enhance-hydrophobic effect on surfaces of optoelectronic devices has attracted attention because of their self-cleaning effect.n the present work, the SWSs combining AR and enhanced hydrophobic effects was reported. A simple method, which combines sub-wavelength-scale monolayer nanospheres (Colloidal lithography) with a reactive ion etching process, to fabricate AR structures of Si nanorod arrays (NRAs) was used. Spectral reflectance measurements of Si substrates with NRA SWSs showed drastic reduction in reflection over a broad range of wavelengths and a wide range of angle of incidence, demonstrating its ability to broadband and omnidirectional antireflection. The reflectivity and the contact angle as a function of diameter, height, slope of Si NWAs were discussed.
Subjects
Anti-reflection
Subwavelength
Colloidal lithography
Reactive ion etching
Nanorod
Contact angle
Type
thesis
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