Electronic structure, dynamic stability, elastic, and optical properties of MgTMN2 (TM = Ti, Zr, Hf) ternary nitrides from first-principles calculations

Abstract

Ternary nitride semiconductors with tunable electronic structure and charge transport properties have attracted increasing attention as optoelectronic materials. The recently discovered ternary MgTMN2 (TM=Ti,Zr,Hf) are predicted to be nondegenerate semiconductors with visible-range optical absorption onsets. In the present study, the electronic structure, elastic properties, optical absorption spectrum, and dynamic stability of the MgTMN2 system have been systematically studied by first-principles calculations based on the density functional theory. These compounds show semiconductor characteristics with a bandgap ranging from 1.0 to 1.5 eV predicted by the Heyd–Scuseria–Ernzerhof approach. Compared to the traditional semiconductors of Si and GaAs and III–V nitrides of GaN and AlN, these ternary nitrides have stronger resistance to external compression, shear strain, and deformation due to the larger elastic modulus. MgTiN2 shows a strong anisotropy characteristic along the xy plane and z axis, while for MgZrN2 and MgHfN2, a weak elastic anisotropy is predicted. The absorption regions of these compounds are mainly concentrated in the ultraviolet region, and MgTiN2 is more sensitive to visible light with respect to the other two compounds. The thermodynamic stability of MgTiN2, MgZrN2, and MgHfN2 is verified by the stable phonon dispersion relations. It is found that the most stable low Miller index surface is (110) for MgTiN2 and (100) for MgZrN2 and MgHfN2.

Experimental Synthesis of Theoretically Predicted Multivalent Ternary Nitride Materials

“…Another distinguishing feature of these rocksalt-derived ternary nitrides is the large static dielectric constant (25−75 ε 0 ) compared to the wurtzite-derived ternary nitrides (5−10 ε 0 ) due to their much stronger ionic component. The Mg−TM−N (TM = Ti, Zr, Hf) GW band gap calculation results 26 are consistent with an HSE study that also calculated their mechanical properties 140 and wider than earlier theoretical studies at the GGA level of theory that also predicted their thermoelectric properties 69 and calculated some defect formation energies. 110 For Mg 2 SbN 3 that crystallizes in a wurtzite-derived rather than rocksaltderived crystal structure, the band gap is much wider (>3 eV) and direct.…”

Carrier transport in bulk and two-dimensional Zn2(V,Nb,Ta)N3 ternary nitrides

“…46 Giant electron mobility up to 10 4 cm 2 V −1 s −1 has been found in ternary nitride MgHfN 2 and MgZrN 2 monolayers. 80 Based on the abovementioned discussion, the electron mobility of 1.67 × 10 4 cm 2 V −1 s −1 in 2D Zn 2 NbN 3 reported in this work is one of the highest values compared to previously reported values for 2D materials.…”

MgXN2 (X = Hf/Zr) Monolayers: Auxetic Semiconductor with Highly Anisotropic Optical/Mechanical Properties and Carrier Mobility

“…Recently, ternary nitride semiconductors have been studied theoretically and experimentally, especially for MgXN 2 (X = Ti, Zr, Hf). − Among the latter ternary compounds, MgZrN 2 and MgHfN 2 share the same tetragonal crystal structure (space group I 41/ amd ) and are 3D materials rather than the layered vdW materials. These ternary nitride compounds exhibit interesting electronic and optical properties.…”