Surface Plasmons in Oxide Semiconductor Nanoparticles: Effect of Size and Carrier Density

Hiroaki Matsui

### Abstract

Oxide semiconductors have received much attention for potential use in optoelectronic applications such as transparent electrodes, transistors, and emitting devices. Recently, new functionalities of oxide semiconductors have been discovered such as localized surface plasmon resonances (LSPRs), which show highefficiency plasmon excitations in the infrared (IR) range using different structures such as nanorods, nanoparticles (NPs), and nanodots. In this chapter, we introduce optical properties of carrier- and size-dependent LSPRs in oxide semiconductor NPs based on In2O3: Sn (ITO). In particular, systematic examinations of carrier- and size-dependent LSPRs reveal the damping mechanisms on LSPR excitations of ITO NPs, which play an important role in determining excitation efficiency of LSPRs. Additionally, the control of carrier and size in the ITO NPs contribute toward improving solar-thermal shielding in the IR range. The high IR reflectance of assembled films of ITO NPs is due to three-dimensional plasmon coupling between the NPs, which is related to electron carriers and particle size of ITO NPs. This chapter provides new information concerning structural design when fabricating thermal-shielding materials based on LSPRs in oxide semiconductor NPs.

Keywords: oxide semiconductor, nanocrystal, plasmon, infrared, energy-saving
