Fabrication and Optical Properties of Au-Coated Polystyrene Nanosphere Arrays with Controlled Gaps

Abstract

Large area monolayer of self-assembled polystyrene sphere (PS) arrays were formed by an interface self-assembly method and the gap of PS was adjusted by O2 plasma treatment (OPT). After different duration of OPT, the spacing between the PSs varied from 5 to 88 nm. Then, 20 nm Au film was deposited on the PS arrays by electron beam deposition. The absorption peaks of Au-coated PS array red-shifted obviously by changing the gap of PS. The new absorption peaks emerged when the gap of the PS decreased to about 20 nm. The surface plasmon resonance (SPR) was employed to explain the absorption proportion of this Au-PS structure. These micro-nano structures exhibit tunable SPR bands, which may be useful to the applications in some research fields, such as biosensing, single molecule detection, and novel optoelectronic devices.