Optical response of nanostructured Ag/Au and Au/Ag bilayer thin films deposited by ion beam sputtering

Abstract

Bilayer metal thin films of total thickness 15 to 20 nm, were deposited by ion beam sputtering at very low ion energy (150 eV-250 eV). The thickness of bottom metal layer was kept constant whereas the thickness of top metal layer were varied in both, Ag/Au and Au/Ag bilayer, cases. There is a red shift in the position of the SPR peak due to the presence of the top metal layer. In the case of Au/Ag the presence of Au causes a shift from 444 nm to 628 nm while in the case of Ag/Au the shift is from 564 to 686 nm due to the presence of the Ag layer on Au. The tunability of plasmon resonances is attributed to the process of plasmon hybridization. © 2011 American Institute of Physics.