Observation of blue shift absorption for surface plasmon resonance in Gold Nano-Islands

Abstract

Controllable and predefined absorption are essential in the synthesis of new optoelectronic devices. In this work, an ion coater unit with a modified chamber is used to sputter the gold nano-islands onto glass substrates. Empirical formula and field emission scanning electron microscope (FESEM) is utilized to estimate the nominal thicknesses of the nano-island. Atomic force microscopy (AFM) images showed low values of roughness for the ultrathin films. The FESEM reveals that most of the nano-islands have round shapes. The UV-VIS measurements demonstrated that gold nano-islands revealed two regimes of absorption. Moreover, the peaks of surface plasmon resonance, in particular, are shifted to longer wavelengths and broadened in width with an increased thickness from 12-120 nm. In reverse to this behavior, the peaks are blue shifted for nominal thicknesses lower than 12 nm. The enhanced absorption in the blue spectral region can be utilized to increase absorption in solid-state solar cells and enhanced the stimulated Raman scattering devices using predefined thickness and deposition parameters.