Fabrication and optical properties of size-controlled Ag nanodot array via nanoporous alumina mask

Ag nanostructure has been widely used for optical sensing applications for localized surface plasmon resonance (LSPR). Many efforts have been tried to fabricate and control silver nanostructure. The pore diameter of the nanoporous alumina mask with through-holes was controlled by two-time dipping in 5 wt% phosphoric acid at 30°C. Using the nanoporous alumina mask as an evaporation mask, size-controlled Ag nanodot arrays were directly formed on indium-tin-oxide coated glass. With this process, Ag nanodot arrays with different size (42 nm, 60 nm, 80 nm) could be fabricated in periodic patterns with same separation distance of 105 nm. A large area Ag nanodot array was fabricated from the hard-won alumina mask. Their LSPR properties are examined by UV-vis extinction spectroscopy.