文摘
Using alternative plasmonic materials, we experimentally demonstrate gap plasmon resonances in metal鈥搃nsulator鈥搈etal nanostructures in the near- and mid-infrared wavelength regions utilizing gallium doped zinc oxide as the metallic component and undoped zinc oxide as the dielectric. We show that similar to metal鈥搃nsulator鈥搈etal resonators previously demonstrated with noble metals, the layered transparent conducting oxide nanodisks support gap surface plasmon resonances characterized by highly confined electromagnetic fields in the dielectric gap. Such resonances can be tailored to desired values by varying the dielectric-layer thickness. Utilizing these observed gap plasmon resonance, we examine the potential of our structure for sensing applications by measuring the surface enhanced infrared absorption of an octadecanethiol layer. The layered nanostructure can detect very weak absorption resonances in nanoscale volumes of absorbing material deposited over the nanodisk resonator.