Infrared Reflectance Spectrum of BN Calculated from First Principles

TL;DR

This paper uses first-principles calculations to analyze the vibrational and dielectric properties of different BN structures, providing detailed infrared spectra and insights into their optical characteristics.

Contribution

It presents a comprehensive first-principles study of BN's vibrational, dielectric, and infrared reflectance properties, including phonon mode analysis and comparison of different BN phases.

Findings

Excellent agreement between theory and experiment for phonon frequencies

All BN structures have smaller lattice dielectric constants than electronic contributions

Infrared spectra of w-BN and c-BN are similar, making phase distinction difficult via IR

Abstract

Using the linear response theory, the vibrational and dielectric properties are calculated for c-BN, w-BN and h-BN. Calculations of the zone-center optical-mode frequencies (including LO-TO splittings) are reported. All optic modes are identified and agreement of theory with experiment is excellent. The static dielectric tensor is decomposed into contributions arising from individual infrared-active phonon modes. It is found that all of the structures have a smaller lattice dielectric constant than that of electronic contribution. Finally, the infrared reflectance spectrums are presented. Our theoretical results indicate that w-BN shows a similar reflectivity spectrum as c-BN. It is difficult to tell the wurtzite structure from the zinc blende phase by IR spectroscopy.