Near-IR Plasmons in Micro and Nanoparticles with a Semiconductor Core

Abstract

We computationally study the electromagnetic response of semiconductor micro and nanoinclusions for realizing highly reflective, plasmonically enhanced coatings in the visible and infrared regime. We first examine the influence of oxide coatings on the Mie resonances of microparticles of low-bandgap semiconductors (Si and Ge) in the near-IR regime. We then study the influence of a semiconducting core on the localized surface plasmon resonances of Si@Ag and Ge@Ag core@shell nanoparticles. Our results show a strong interaction between the resonances of the plasmonic Ag shell and the semiconducting core material which allows tuning of the electromagnetic response for near-IR applications.

Directing Near-Infrared Photon Transport with Core@Shell Particles

“…The shell thickness varies along the y-axis and the dark blue areas indicate the wavelengths where the magnitude of Q sca is large. The oxide coating dampens the magnitude of Q sca compared to bare particles, 34,36 and yet the optical behavior of the layers is influenced by factors such as the alignment of the scattering modes with the discrete near-IR solar spectrum and the direction and magnitude of scattered field. These factors are discussed below.…”

“…This material effect is expected due to the value of m 2 , the relative refractive index of oxide shell and the medium, which is greater than one for ZrO 2 -and TiO 2 . 34,36 The shifting of the scattering modes affects the alignment with the incident solar spectrum. There are minor fluctuations in the maximum reflectance efficiencies between the different oxides in Figure 2A, C, but the effect is more clearly observed in the single particle scattering efficiency, Q sca , with a fixed core particle radius.…”

“…The scattering by the semiconductor@oxide particles is more efficient for oxides having larger relative refractive indices of the shell and medium. 34,36 The magnitude of the scattering is exhibited in the higher reflectance efficiency of layers containing ZrO 2 -or TiO 2 -coated particles than layers embedded with SiO 2 -coated particles (Figures 2A, C and S4). The effect is more pronounced at large oxide filling fraction.…”

Broadband Tunable Mid-Infrared Absorber Based on Conductive Strip-Like Meta-Atom Elements

“…Interaction of electromagnetic radiation with subwavelength metal particles and controlling for optical processes such as absorption and scattering is of great interest for both fundamental science and practical applications [1][2][3]. Particularly, the realization of the high absorption with a simultaneously low scattering in systems consisting of metal particles is important for energy harvesting and conversion [4,5], optoelectronics [6], sensing [7] and investigations of light-matter interactions [8]. Nanoparticles with various shapes, such as spheres, cubes, rods, discs etc.…”