Raman and Infrared Signatures of Layered Boron Nitride Polytypes: A First-Principles Study

We present a detailed first-principles investigation of the vibrational and spectroscopic properties of four layered boron nitride (BN) polymorphs–e-BN (AA), h-BN (AA′), r-BN (ABC), and b-BN (AB). Using density functional perturbation theory with van der Waals corrections, we calculate phonon frequencies and Raman and infrared (IR) modes at the Γ point to identify distinct stacking-dependent spectral signatures. Our results reveal that r-BN exhibits the strongest combined Raman and IR response, dominated by a high-frequency E mode at 1399.9 cm−1, while e-BN is characterized by a sharp, isolated E′ mode at 1402.4 cm−1. In h-BN, the characteristic E2g Raman mode at 1396.7 cm−1 is accompanied by a unique mid-frequency A2u IR mode at 704.4 cm−1. The b-BN polytype shows its most distinctive IR feature at 728.3 cm−1 (A2′′), together with a high-frequency E′ Raman/IR mode at 1409.5 cm−1. These spectroscopic fingerprints provide a reliable means to distinguish BN polytypes and directly support recent experimental efforts to determine stacking order via vibrational spectroscopy. This study establishes a robust theoretical framework for interpreting Raman and IR spectra of BN polymorphs and guiding the characterization of layered sp2-bonded materials.