Ab initio calculations of the structural, electronic and elastic properties of the MZN2 (M=Be, Mg; Z=C, Si) chalcopyrite semiconductors

TL;DR

This study uses first principles calculations to analyze the structural, electronic, optical, and elastic properties of four chalcopyrite semiconductors, revealing their indirect band gaps, anisotropic behaviors, and potential for high-hardness applications.

Contribution

It provides the first ab initio analysis of these specific MZN2 chalcopyrite semiconductors, highlighting their anisotropic properties and potential applications.

Findings

All materials are indirect band gap semiconductors with gaps 3.46-3.88 eV.

Optical and elastic anisotropies are correlated, especially in MgSiN2.

Materials exhibit high hardness with bulk moduli up to 300 GPa.

Abstract

Four ternary semiconductors with the chalcopyrite structure (BeCN2, BeSiN2, MgCN2, and MgSiN2) were studied using the first principles methods. The structural, electronic, optical and elastic properties were calculated. All these materials were found to be the indirect band gap semiconductors, with the calculated band gaps in the range from 3.46 eV to 3.88 eV. Comparison of the degree of covalency/ionicity of the chemical bonds in these compounds was performed. Anisotropy of the optical properties of these tetragonal crystals was demonstrated by calculating the real and imaginary parts of the dielectric function {\epsilon}. Anisotropy of the elastic properties of these materials was analyzed by plotting the three-dimensional dependences of the Young moduli and their two-dimensional cross-sections. It was also shown (at least, qualitatively) that there exists a correlation between the optical and elastic anisotropy: the most optically anisotropic MgSiN2 is also most elastically anisotropic material in the considered group. High hardness (bulk moduli up to 300 GPa) together with large band gaps may lead to new potential applications of these compounds.