Dual-band plasmonic resonance-enhanced absorptance in Au/Si:Te heterostructures for mid-infrared applications

This work reveals enhanced infrared optical properties in plasmonic Au/Si:Te heterostructures, where hyperdoped Si:Te layers fabricated via Te ion implantation and flashlamp annealing exhibit ∼20% broadband sub-bandgap absorption across 2–5 μm. Integration with Au nanostructures induces dual plasmonic resonances at 2.7 and 4.4 μm, boosting peak absorptance to 52%–83%. Electromagnetic simulations attribute this enhancement to plasmon-dielectric hybridization, where strong near-field amplification at the Au/Si:Te interface intensifies mid-gap state transitions in Si:Te. Concurrently, resonant energy transfer occurs, as grating-confined surface plasmons concentrate incident radiation, enhancing photon-impurity interactions. Geometric tuning further enables spectral selectivity with wavelength-specific absorption enhancement. The hyperdoped Si:Te heterostructures demonstrate complementary metal-oxide-semiconductor-compatible tailoring of light-matter interactions through hybrid plasmonic and impurity-band effects.