On the splitting of the surface plasmon resonance band of gold nanopillars developed on rippled Si surface

Abstract

In this work, we reported split surface plasmon resonance (SPR) bands originated from the Au nanopillars developed on rippled Si substrates. This is the first report of gold SPR splitting on a pre-structured Si surface. The Si surface was subjected to a bombardment of Ar ions to fabricate ripples on the surface. A 5 nm thin layer of Au was then deposited on the rippled surface, and the SPR was studied using UV–visible spectroscopy. Further, X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure spectroscopy (EXAFS) were used to characterize the prepared samples. The AFM confirmed that the deposited gold is in nanopillar form, and the rippled surface governs the growth, shape, and size of gold nanopillars. A large aspect ratio has been observed for the nanopillars, resulting in a red-shifted and split SPR band. The experimental XANES of Au L3-edge were successfully mimicked by simulated XANES, confirming the existence and signature of the nanostructure. For the first time, the local structure information of Au nanopillars constructed on rippled Si substrate has been obtained using the EXAFS approach in different directions and correlated with the plasmonic bands.