First-principles study of infrared, Raman, piezoelectric and elastic properties of Mg-IV-N\textsubscript{2} (IV = Ge, Si, Sn)

TL;DR

This study uses first-principles calculations to analyze the vibrational, optical, piezoelectric, and elastic properties of Mg-IV-N₂ compounds, revealing their potential for electronic and optoelectronic applications.

Contribution

It provides detailed vibrational mode analysis, phonon dispersions, and tensor properties for Mg-IV-N₂ compounds using DFPT, which were previously unreported.

Findings

Vibrational modes at zone center linked to point-group symmetries.

Full phonon dispersion and density of states calculated.

Piezoelectric and elastic tensors determined for the materials.

Abstract

Mg-IV-N\textsubscript{2} compounds with IV=Si, Ge, Sn are ultra-wide band gap semiconductors with various potential electronic and optoelectronic applications. They share the \textit{Pna}2\textsubscript{1} space group crystal structure. Here we present Density Function Perturbation Theory (DFPT) calculations of the vibrational modes of these materials. We focus on the vibrational modes at the zone center to establish the relation between vibrational modes and their corresponding point-group symmetries, which determine the Raman and infrared spectra but also report the full Brillouin zone phonon dispersions and density of states. We also determine the piezoelectric tensor and the elastic compliance tensor.