Boundary-induced auxiliary features in scattering-type near-field fourier transform infrared spectroscopy

Jiong Yang, Mohannad Mayyas, Jianbo Tang, Mohammad B. Ghasemian, Honghua Yang, Kenji Watanabe, Takashi Taniguchi, Qingdong Ou, Lu Hua Li, Qiaoliang Bao, Kourosh Kalantar-Zadeh

Research output: Contribution to journalArticleResearchpeer-review

10 Citations (Scopus)


Phonon-polaritons (PhPs) in layered crystals, including hexagonal boron nitride (hBN), have been investigated by combined scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared (FTIR) spectroscopy. Nevertheless, many of such s-SNOM-based FTIR spectra features remain unexplored, especially those originated from the impact of boundaries. Here we observe real-space PhP propagations in thin-layer hBN sheets either supported or suspended by s-SNOM imaging. Then with a high-power broadband IR laser source, we identify two major peaks and multiple auxiliary peaks in the near-field amplitude spectra, obtained using scattering-type near-field FTIR spectroscopy, from both supported and suspended hBN. The major PhP propagation interference peak moves toward the major in-plane phonon peak when the IR illumination moves away from the hBN edge. Specific differences between the auxiliary peaks in the near-field amplitude spectra from supported and suspended hBN sheets are investigated regarding different boundary conditions, associated with edges and substrate interfaces. The outcomes may be explored in heterostructures for advanced nanophotonic applications.

Original languageEnglish
Pages (from-to)1123-1132
Number of pages10
JournalACS Nano
Issue number1
Publication statusPublished - 28 Jan 2020


  • boundary
  • hBN
  • nano-FTIR
  • near-field
  • phonon-polariton
  • s-SNOM imaging
  • scattering-type nanoIR

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