Probing Symmetry and Helicity Insights into h-BN Phonon Modes using Polarized Raman Spectroscopy

Shih-Po Chien^1*, Yu-Chen Chang¹, Shantanu Saha², Shamsul Arafin², Ting-Hua Lu², Yann-Wen Lan¹

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan
²Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, USA

* Presenter:Shih-Po Chien, email:rn487801@gmail.com

Hexagonal boron nitride (h-BN) has gained significant attention in the realm of two-dimensional electronic devices due to its atomic-thin insulating properties. This study explores the impact of polarized incident light on the optical characteristics of h-BN phonon modes, employing polarized Raman spectroscopy. Our findings reveal that linearly polarized light induces symmetry, while elliptically polarized light splits the degenerate phonon modes in h-BN. Furthermore, we observe a fascinating helicity exchange between circularly polarized light excitation and the resulting opposing circular polarization of scattered light from h-BN. To interpret these phenomena, we employ Raman tensors and Jones calculus, enabling the calculation of amplitude coefficients for two orthogonal in-plane phonon modes. This research enriches our understanding of h-BN's vibrational modes, with implications for comprehending its physical properties, including heat capacity, thermal conductivity, and electrical conductivities.

Keywords: Hexagonal Boron Nitride, Polarized Raman Spectroscopy, Helicity Exchange, Broken Symmetry, Two-Dimensional Materials