Boron Isotope Effects on Raman Scattering in Bulk BN, BP, and BAs: A Density-Functional Theory Study

TL;DR

This study uses density-functional theory to analyze how crystal structure and boron isotope disorder affect Raman spectra in BN, BP, and BAs, providing insights into phonon behavior relevant for quantum and thermal applications.

Contribution

It introduces a comprehensive theoretical approach to understand isotope and structural effects on Raman spectra in BX compounds, aligning well with experimental data.

Findings

Long-range Coulomb interactions influence Raman spectra evolution.

Boron isotope substitution causes frequency shifts and peak broadening.

Results aid in interpreting phonon behavior for quantum and thermal applications.

Abstract

For many materials, Raman spectra are intricately structured and provide valuable information about compositional stoichiometry and crystal quality. Here we use density-functional theory calculations, mass approximation, and the Raman intensity weighted $\Gamma$-point density of state approach to analyze Raman scattering and vibrational modes in zincblende, wurtzite, and hexagonal BX (X = N, P, and As) structures. The influence of crystal structure and boron isotope disorder on Raman line shapes is examined. Our results demonstrate that long-range Coulomb interactions significantly influence the evolution of Raman spectra in cubic and wurtzite BN compounds. With the evolution of the compositional rate from $^{11}$B to $^{10}$B, a shift toward higher frequencies, as well as the maximum broadening and asymmetry of the Raman peaks, is expected around the 1:1 ratio. The calculated results are in excellent agreement with the available experimental data. This study serves as a guide for understanding how crystal symmetry and isotope disorder affect phonons in BX compounds, which are relevant to quantum single-photon emitters, heat management, and crystal quality assessments.