Temperature-resilient anapole modes associated with TE polarization in semiconductor nanowire

TL;DR

This study uses numerical modeling to explore how temperature and polarization affect optical anisotropy in semiconductor nanowires, revealing temperature-resilient anapole modes in TE polarization with potential applications in sensing and microscopy.

Contribution

It demonstrates the existence of temperature-resilient higher-order anapole modes in semiconductor nanowires, highlighting their potential for stable optical applications under temperature variations.

Findings

Semiconductor nanowires exhibit temperature-dependent plasmonic resonances.

TE polarization anapole modes are temperature-resilient in semiconductor nanowires.

GaAs nanowires show significantly higher absorption efficiencies than Si nanowires.

Abstract

Polarization-dependent scattering anisotropy of cylindrical nanowires has numerous potential applications in, for example, nanoantennas, photothermal therapy, thermophotovoltaics, catalysis, sensing, optical filters and switches. In all these applications, temperature-dependent material properties play an important role and often adversely impact performance depending on the dominance of either radiative or dissipative damping. Here, we employ numerical modeling based on Mie scattering theory to investigate and compare the temperature and polarization-dependent optical anisotropy of metallic (gold, Au) nanowires with indirect (silicon, Si) and direct (gallium arsenide, GaAs) bandgap semiconducting nanowires. Results indicate that plasmonic scattering resonances in semiconductors, within the absorption band, deteriorate with an increase in temperature whereas those occurring away from the absorption band strengthen as a result of the increase in phononic contribution. Indirect-bandgap thin ($20 \,\mathrm{nm}$) Si nanowires present low absorption efficiencies for both the transverse electric (TE, $E_{\perp}$) and magnetic (TM, $E_{\parallel}$) modes, and high scattering efficiencies for the TM mode at shorter wavelengths making them suitable as highly efficient scatterers. Temperature-resilient higher-order anapole modes with their characteristic high absorption and low scattering efficiencies are also observed in the semiconductor nanowires ($r \! = \! 125 \! - \! 130$ nm) for the TE polarization. Herein, the GaAs nanowires present $3 \! - \! 7$ times greater absorption efficiencies compared to the Si nanowires making them especially suitable for temperature-resilient applications such as scanning near-field optical microscopy (SNOM), localized heating, non-invasive sensing or detection that require strong localization of energy in the near field.