Sputtering and plasma exposure to fabricate gold nanoparticles with clean surfaces

Kawaguchi, Kazuhiro; Sanari, Takumi*; Takahiro, Katsumi*; Yamamoto, Shunya; Yoshikawa, Masahito; Nagata, Shinji*

Silver (Ag) and gold (Au) nanoparticles have strong optical extinction band due to localized surface plasmon resonance (LSPR) in the visible range. These nanoparticles on transparent substrates are being applied to chemical and biological sensors, in which changes in the LSPR features, including resonance wavelength, width and intensity, are observed. In such applications, an intense and sharp absorption band is required for higher detection sensitivity. Our previous work showed that a plasma treatment could be an effective tool to control the LSPR features for Ag nanoparticles prepared by sputter deposition. In the treatment, argon (Ar) plasma cleans up impurities adsorbed on the Ag nanoparticles, resulting in the blue shift and sharpening of the LSPR. In the present work, sputter deposition, and plasma have been employed to fabricate Au nanoparticles with desired optical properties for plasmon-based sensors.