Nanoplasmonic Excitations and Carrier Control in Oxide Semiconductors

Abstract

Oxide plasmonics have received much attention as new phenomena with potential applications in optical fields as diverse as energy-harvesting and sensing devices. Semiconductor materials (In2O3 and ZnO)are expected for alternative plasmonic nanomaterials in the near- to mid-infrared range. In this work, optical properties of carrier-dependent local surface plasmons (LSPs) were investigated using dopant-controlled In2O3: Sn nanoparticles (NPs). From a systematic correlation between LSP excitations and electron carriers, electron-impurity scattering contributed towards plasmon damping as one of a factor that is absent in metal NPs. A threshold electron density (ne) from a damping dominated regime to a quenched damping regime appeared at around 1020 cm‒3. The validity of Mie theory failed in ITO NPs with high ne greater than 1020 cm‒3 since the role of electron carriers could enhance LSPs with simultaneous damped plasmonic excitations, which is valuable information to realize plasmonic nanomaterials with high performance based on oxide semiconductors.