Enhanced Far-Field Emission Via Dual Reststrahlen Bands in h-BN/SiO<sub>2</sub> Bilayer.
basic_science · Level V
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- Record sourced from PubMed, PMID 41937613.
- Also identified by DOI 10.1021/acs.nanolett.6c00126.
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Abstract
Highly confined phonon polaritons enable strong light-matter interactions that tailor incandescent heat sources for enhanced thermal emission in both the near- and far-field regimes. However, single polar dielectric materials are limited in both the emission spectral range and achievable mode confinement. In this study, we employ a bilayer structure comprising monolayer hexagonal boron nitride (h-BN) integrated with silicon dioxide (SiO<sub>2</sub>) to exploit confined phonon polariton modes across a broadened energy spectrum. The distinct, nonoverlapping Reststrahlen bands of h-BN and SiO<sub>2</sub> provide multiple spectral channels for polaritonic enhancement, improving far-field emission. We report a 3.4-fold enhancement in emissivity with the addition of h-BN to a SiO<sub>2</sub> nanoribbon. We identify the confined modes within the Reststrahlen bands with numerical modeling, revealing the enhancement mechanism. This effect is verified with direct thermal measurements by using a thermal bridge method, yielding a peak emissivity of 0.6. This work offers insights into engineering broad-band polaritonic thermal emitters.