Hexagonal boron nitride (h-BN) has been predicted to exhibit an in-plane thermal conductivity as high as ~ 550 W m−1K−1at room temperature, making it a promising thermal management material. However, current experimental results (220–420 W m−1K−1) have been well below the prediction. Here, we report on the modulation of h-BN thermal conductivity by controlling the B isotope concentration. For monoisotopic10B h-BN, an in-plane thermal conductivity as high as 585 W m−1K−1is measured at room temperature, ~ 80% higher than that of h-BN with a disordered isotope concentration (52%:48% mixture of10B and11B). The temperature-dependent thermal conductivities of monoisotopic h-BN agree well with first principles calculations including only intrinsic phonon-phonon scattering. Our results illustrate the potential to achieve high thermal conductivity in h-BN and control its thermal conductivity, opening avenues for the wide application of h-BN as a next-generation thin-film material for thermal management, metamaterials and metadevices.
Phonon‐polaritons, mixed excitations of light coupled to lattice vibrations (phonons), are emerging as a powerful platform for nanophotonic applications. This is because of their ability to concentrate light into extreme sub‐wavelength scales and because of their longer phonon lifetimes compared to their plasmonic counterparts. In this work, the infrared properties of phonon‐polaritonic nanoresonators made of monoisotopic10B hexagonal boron nitride (h‐BN) are explored, a material with increased phonon‐polariton lifetimes compared to naturally abundant h‐BN due to reduced photon scattering from randomly distributed isotopes. An average relative improvement of 50% of the quality factor of monoisotopic h‐BN nanoresonators is obtained with respect to nanoresonators made of naturally abundant h‐BN, allowing for the sensing of nanometric‐thick films of molecules through both surface‐enhanced absorption spectroscopy and refractive index sensing. Further, even strong coupling between molecular vibrations and the phonon‐polariton resonance in monoisotopic h‐BN ribbons can be achieved.
more » « less- NSF-PAR ID:
- 10453850
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 9
- Issue:
- 5
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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