Modulating phonon-electron Fano resonance in Si nanoparticles through laser exposure and properties of surrounding nanoparticles

Abstract

This study presents scalable and cost-effective methods for precisely modulating the phonon-electron Fano resonance in silicon (Si) nanoparticles, with potential applications in sensing, quantum technologies, and energy devices. Beyond conventional approaches reliant on laser intensity, we demonstrate that the Fano resonance can be enhanced by prolonged laser exposure, which increases electronic transitions to energy levels induced by band-edge disorder, and by strong electromagnetic field confinement achieved through multiple light scattering by non-absorbing surrounding particles. Conversely, the Fano resonance strength can be attenuated by introducing anharmonic decay channels for Si optical phonons, driven by anharmonic interactions between Si phonons and phonons of surrounding nanoparticles. These interactions disrupt the coherence essential for a strong Fano resonance, providing a controllable mechanism for weakening the effect. Experimental validation is achieved using Si nanoparticles embedded in granular media composed of zinc oxide (ZnO), monoclinic gallium oxide (β-Ga₂O₃), and graphite (C). By leveraging laser exposure, electromagnetic field confinement, and tailored nanoparticle environments, this work offers versatile and scalable strategies for advancing photonics, optoelectronics, thermoelectrics, and Raman-based sensing technologies.